Your post nothing but thinly-veiled FUD. I can't even tell what point you are trying to make, as your arguments aren't at all analogous to a social network.
An OSS Facebook will have hundreds of competing distros,
There are very few serious distributions that compete for the same niche market.
several dozen kernel forks,
Most distributions commit kernel fixes back to upstream or backport them to older versions.
Countless different versions of the standards that developers will argue over for years
Compared to what?
It's pretty well known that you should never let programmers design user interfaces.
and no documentation
I've used a lot of free software so far, and it's extremely rare that there is no documentation. Just because it's not in your preferred format, doesn't mean it's non-existent.
New users wishing to convert over from commercial Facebook will be told "Well, first you have to decide if you want to go with a RTH, KJG, RTY, or TTTY desktop interface; then you need to pick a client from this list which you can download from this obscure irc channel; then you need to config it to your router and find the drivers for your system; and you might also need to download and install Java, Greasemonkey, and a compiler to create binaries for your particular OS" and presented with a long list of bug fixes in lieu of a user manual.
Despite your example being exaggerated, I've never had to do anything so ridiculous using any free operating system. I'm willing to accept that a minority of applications have less than perfect installation procedures, but fortunately, there is rarely a shortage of alternatives in the free software world -- you can often find something better.
And before you mod me troll, know that this is exactly what Linux (and plenty of other OSS) looks like to a non-geek user.
What does a non-geek need to know about kernel versions, distributions etc. to use Ubuntu for their non-geek activities (i.e. web browsing, writing documents and listening to music)? All these activities are possible with the default installs.