Linux has had 20 years to prove itself, clearly it is not the right solution, or it would have made some traction at this point...
Yes . . . and it has. Hell, even demonstrated by the article in question here, or does "a big enough audience to justify day-one releases of AAA games" not count somehow?
Now, convincing me that an LCD touchscreen watch makes any sort of sense, that's another story. The Pebble is, generally, just everything a normal watch is with a little bit of extra on top. Anything that sacrifices outdoor legibility or battery life, however? Yeah, that's just companies desperately hunting around for the next big boom market because our insane society has decided that profits must always increase, and stability is somehow death.
Alas, electronics have not yet advanced to the point where it is reasonable to have one phone with support for all combinations of bands and technologies.
Right before LTE started rolling out, and before Nokia was forced to adopt chipsets approved for Windows Phone rather than using their own, the high-end Nokia devices developed had pentaband 3G and quadband 2G, which covered nearly everything (sure, some rural places in very few countries were CDMA, but this was already rare). It seemed then like other manufacturers might catch up. Unfortunately, with LTE we've re-fragmented, and manufacturers have used it as an excuse to go back to selling different models for different markets/carriers.
See https://community.kde.org/KDE/High-dpi_issues. In fairness, most (in fact, the overwhelming majority) of elements within KDE are resolution independent (hell, KDE has been using SVG icons since well before the KDE4 days), and basically every element can be changed and tweaked as desired, it's just that it takes a shit ton of annoying manual tweaking.
You're right though, it Isn't There Yet (tm). But it is in fact a focus of much of the development; this is generally on the minds of KDE devs, and is being worked towards for Plasma Next, as well as for specific applications; for example, the Yakuake developer is changing the theming engine specifically with resolution-independence and high-DPI screens in mind. So upcoming versions of KDE will be, at very least, closer to supporting high DPI and resolution independence, and I wouldn't be surprised at all if a version or two into Frameworks 5 we get a nice centralized control for scaling the UI.
The Tao is like a glob pattern: used but never used up. It is like the extern void: filled with infinite possibilities.