- work/school productivity users were predominantly tied to Win/Mac.
- basic functionality was a mess in the past.
- Game development has been so heavily tied to either consoles or Windows.
- Desktop and game dev sdks have been a mess.
Linux has turned a corner on the first two. Android/iOS have completely blown the third item out of the water. The fourth one is making progress as well. Valve has had some contribution, but it's been minor and these things would have happened without them.