Yeah, Windows managed to break that only really cool characteristic it had: back compatibility. Well, their loss.
90%
Nah. Do you really believe in that? Yes, Unity and Unreal based games are mostly(!) runnable. Anything else is very problematic. Where did you even get that 90% number? From Proton advertisements?
“Unsanctioned copying” gives me a big pile to choose from, but in reality I still have nothing. For example I like computer games, but I use Linux, so 2/3 of titles are unplayable. 90% of rest are things that are completely not interesting to me. I am lucky if I can find something playable once or twice per month.
I really don’t feel your problem.
I don’t actually remember when it was the last time I heard about divx. 10-15 years ago? I think that the title is clickbait and overdramatization.
Is it somehow important for Linux?
They expectedly don’t serve to barbarians.