Also the user isn't under warranty.

(that might explain because most of them are crap)

Stupid planned obsolescence. We should complain to the manufacturer.

I would indeed agree with your first post and this part. To me, a big conspiracy to manipulate results is far less likely than simply slopiness of a mass-produced good, where speed of production counts, in order to quickly meet the demand.

To quote a variant of Hanlon's Razor (often attributed without sources to Napoleon Bonaparte):
"Never ascribe to malice what can adequately be explained by incompetence."

Yup very probably. Specially with modern card that try to go as fast as they can, while still within target thermal envelope.

The problem, is that AMD got too busy doing legitimate improvement under contract for the coming generation of consoles (Xbox One, Play Station 4, and some of the upcoming Steam Box, all run the same combo of AMD CPUs and GPUs).
With that work, there was going to be some delay for their PC's Radeon HD 8xxx serie.

So it was either:
- have absolutely nothing to sell.
- do some small upgrade on the older board (R2 270/280 are simply older board slightly upgraded) and older chips (R2 290(X) are GCN1.1 chips, slightly newer than the GCN1.0) and have something to sell until the real new gen comes, while still taking advantage of the time to add some improvements.

Note that this was pretty much announced that way, and well known for people in the field.

now look at the bright side of the things:
even if they are coming with some delay, that means that next year, you're going to finally see the newer GCN2.0 chip based card, that have taken advangtage of all the R&D done for consoles to improve the performance and quality for radeons.

A little bit later, but a little bit more R&D money poured on the steps leading to them (specially the latest step)

It's well known that these cards operate at a fixed temperature and push the clock and voltage as high as they can within these thermal limits.
It's so well known among professionnal, that some like Tom's are giving advice about BIOS replacement (newer have better and more consistent throttling or fan accross all the varied parts) or thermal paste replacement (to improve cooling and thus performance).

Now add in the mix that some parts, like fans, might be sourced from several different manufacturer (and according to source, BIOS wasn't until latest update so good at operating them), add also that there might be variation in quality between the different batches of thermal paste (which got very probably sourced from several productors) and the output variation is clearly expected.

But also fixable (newest BIOS to compensate fans with better throttling, manually replace thermal paste. Now cards works as good as benchmarking sample or even better)

Not that BIOS. As other have pointed in the thread, the variation in performance is more or less linked to the variance of thermal management.
Not all PWM Fan behave the same. There's a *newer* BIOS version (not as in "use the one that came with the sample" but as in "download the latest version that was made available on the manufacturer website, betwen when you bought it and now").
This version of BIOS is better at computing what signal it should send to the fan to have better cooling.
And once the cooling is improvent, the card will automatically scale up its speed.

Also, there can be difference in thermal grease, etc.

Or, instead of cherry-picking, maybe there's some build quality between the first engineering sample sent by AMD, and the mass-produced card by NONAME asian manufacturer ? (Or even mass-produced cards by very popular brands that have to fulfill lots of orders ?)

Difference in quality of the fans (NONAME will pick whatever is currently the cheapest, and even with popular big-names, there's going to be some variance, depending on where the current batch was sourced).
Difference in quality of thermal conduction of the interface. Difference of quality of thermal grease (NONAME will pick the cheapest, bigname might have variation in batches, specially if they source batch from several manufacturer to keep up with the pace). Difference in quality of work (NONAME might even do a sloppy job in applying the thermal medium to the radiator).

You end up with exactly the same chip produced by AMD, but vastly different thermal condition, all this with a firmware and a driver which isn't yet best at fan throttling, and you end-up with some measurable difference in output. ...BUT...

Pick up Nvidia cards, and you're going to see exactly the same effect.

Either card that vary in their performance (or that have big variation in temperature, depending on how the current firmware throttles the card)

You're joking but that's more or less what's happening.

There are lots of alt-coins in addition of bitcoin.
Some are easier to mine on GPU than other.

You need to pick up a coin that plays well with it.

And another dab coming (underhanded) at Apple in TFA:

Unlike Apple's Lightning port, current and future USB connection have decent bandwidth, and thus can drive a HDMI-out USB-chip to display HD (when they're not directly speaking 'MHL' instead of USB, directly to the display over a dump cable).

And the Lightning port actually isn't a connector, just a direct internal bus. Whatever the iPhone speaks to the outside world is handled by a small chip in the cable or dongle.

In theory, the "pros" given by Apple are:
- evolutive. If a new form of connection arrivers (say for exemple USB3.2 over these new reversible connector), no need of any change in the iPhone itself, just get a new different dongle with an USB3.2 controller inside and a new-gen connector.

In practice, there are tons of "cons" :
- Non standard. (of course, that's apple)
- Mandatory chip (controlled and licensed by Apple) in every single thing that you connect. There can't be a dumb cable, you need a controller.
- Awful bandwith. Lightning's bandwith sucks, it can't be used to drive a display. Current HD-video out dongles have been found to be sorts of "AirPlay": video stream is (destructively) compressed using the accelerated hardware inside the iPhone, the compressed stream is output through the lightning port, the HD-Video out dongle contrain a full blown ARM SoC with integrated graphics which decompresses the video stream and outputs it on its own HDMI connector.
(Cue-in problem with generational compression, over expensive dongle hardware, etc.)

I think the parallel with Linux is valid on a lot of point.
Not only have recent history seen an explosion of variants:
(There are many alt-coins just as there are many linux distributions).
But on the long term, probably is will resolve itself in the same way:
A couple of widespread mainstream variants (like Debian, Redhat, Ubuntu, openSUSE) (same in the crypto-coin world: Bitcoin and Litecoin are apparently here to stay, and happy at their position)
A few others for more specialist uses (like Gentoo, Knoppix, SystemRescueCD) (probably in the crypto world some *actually anonymous* coin will emerge).
And then a whole bunch of entries that nobody has ever heard of and are almost not used.

But there's a small difference:
- Low popularity linux distro, end up usually abandonned
- Whereas, low use coins end up being the playground for troll-traders.

with one small difference:
- With Bank, your only choice is trying to find one that you can trust.
- With crpyto-currencies, you can also run your own node and in a way be your own bank.

In that case, you can trust yourself that you're note going to scam yourself.
And you also know more or less what security measures you're using

Bitcoin's concept of wallet simply adds the users as a possible element in the equation.

As a small addendum to what rasmusbr has already said:

The short answer is yes. The long answer is a little bit more complicated.
If hacker still has copy of the wallet.dat file, the coin could still be stolen (in theory the file can optionnally be encrypted. In practice we all know how good humans are at picking good passwords).

key pairs in a wallet can also be generated using passphrases (so called brain wallet).
in theory the owner is the only one to know the passphrases generating the key pair and thus the only one able to use the private key.
in practice, again, we all know how good humans are at that task
(and before you ask: yes someone has decided to make a keypair using xkcd's "correct horse battery staple" comic).

worst citizens are the web services. they use their own wallet to process coin. you sent an amount to them, and then they process on your behalf. (some even allow you to upload key pairs). You have to trust that they are honnest people. You have also to trust their security measures that their key don't get stolen.

So out of all the various "lost" coins, some are possibly going to re-appear due to poor password strategies, or due to less scrupulous online companie which will decide to re-purpose un-claimed bitcoin account, or outright scam people into giving them coins and then running away with them.

It has already been done. And far more than once.

That not the only incorrect thing.

The mined coin isn't bitcoin, it's protoshare.

But instead of actually mining *Bitcoin* (have no idea where that idea came from) which will probably bring you 10$ a day,
do like TFA and install something which mines a different alt-coin powered by an algorithme which only runs on CPUs.

TFA's example is actually a Protoshare miner.

PrimeCoin is another example which is still mined mostly on CPUs (and in addition to mining also produce scientific data)

Then there are stuff like Quark Coin which use all the candidate for SHA-3 as hashing algo (and don't have good GPU implementation yet, and no ASICs at all).