So this is another Handmade series that you need to extrapolate knowledge if you want to follow on Linux, right? Nothing against it, of course, but, since I'm new to game programming, trying to learn SDL as I learned this stuff back in Handmade Hero was a huge pain, I couldn't get past the 14th episode or so.
The port to Linux will happen later. I forget the exact episode Casey justifies this but basically the problem for game developers is that every other platform other than Window is not a good target platform if you want to stay in business. So he's showing people how to target Windows first and will show us how to port later.
Just go look at the Steam hardware survey to find out why.
I believe Aristoteles said something on those lines a long time ago. I don't see this flipping anything on its head. The conventional function-driven thought of the human being, as if everyone had to perform a duty, and to make the world better - and, even if they had to, what exactly makes the world better? For the sheep, a world without eagles would be better - but the eagles aren't bad, they just have to eat.
Or, maybe, I just didn't understand what he meant =]