Many missing, sure, but at least we have started getting titles from the more known publishers and developers: Dirt Rally, Alien Isolation, Pillars of Eternity, Sid Meier's Civilization VI, Total War: WARHAMMER, Hitman, BioShock Infinite, XCOM 2, Deus Ex: Mankind Divided, Mad Max, Dying Light, Torment: Tides of Numenera, and Valve's own games.
As for numbers, there are 1950 Linux games on GOG and 6000+ on Steam.
You can install Steam and NVIDIA proprietary drivers just fine on Arch Linux or any other distro, as well.
Ubuntu is the only officially supported distro, as in mentioned in system requirements, just because it's the most ubiquitous distro. It doesn't actually mean you will have any less problems with the problematic Linux games on Ubuntu, than on any other distro.
On Arch, with an NVIDIA card, getting this "all" up and running boils down to: sudo pacman -S steam nvidia
This gives you the most recent NVIDIA driver, 378.13-5.
That says more about you as a developer than SO. In just about any SO answer I find numerous things that are either wrong or bad advice. The difference between me and a lot of SO users, especially novices, is that they don't know a good answer from a bad one.
A lot of people on SO seem to be answering just for points, half the time, or more, they don't actually know what they are talking about all or have experience with what they are explaining; they have often literally just "researched" the question and now they condense a couple of sources into an answer. Without having a proper understanding of the subject.
SO is bad for the whole industry. And there is not much that is worse than a "developer" copying an answer off SO and putting it into a production code base, without even understanding the answer they just copied.
He got a programming job without a CS degree. There are so many programmers working without any degree, I fail to see why this blog post was worth writing and posting anywhere. Nothing special here.
Actually he does not even state that the job he got was a programming job, just that it was his "dream job." But what makes it a dream job?
This is incorrect. SO is polluted with "noob" questions and answers, which is why SO is so useless. Google and now even MSDN search results are also polluted with SO hits which are mostly just noise. If anything SO needs more strict moderation.