Lol, tell that to Valve.

I'm not sure what 'most apps' constituted in their case, but I've been playing all my games on Linux for the last 3 years and can't be happier.

I wonder, what prevents better support for 'regular' apps? Are they using some windows API that is hard to implement in Linux?

More resources were put into gaming api’s by Valve, that is all.

Games are usually created from the beginning with cross-platform in mind. So, not as coupled.