Technically speaking I'm sure you're right. In practice it doesn't really matter though, if they did it that way it's either because it was easier or because that's the way they were used to doing it. The fact that "technically" it's not Linux's fault doesn't really matter, unless you're more interested in the moral concept of guilt rather that the practicalities of making a Linux port of a game.
Why should they change the way they develop games for 0.1% of their sales? So that they'd get kudo "clean code" points from people on HN? Most for-profit software cares very little about that, and for good reasons.
Gaming on Linux sucks because Linux is not popular for gaming. Linux is not popular for gaming because gaming on Linux sucks. That's the root of the issue.
Why should they change the way they develop games for 0.1% of their sales? So that they'd get kudo "clean code" points from people on HN? Most for-profit software cares very little about that, and for good reasons.
Gaming on Linux sucks because Linux is not popular for gaming. Linux is not popular for gaming because gaming on Linux sucks. That's the root of the issue.