You still need legacy input for Window interactions, and the message queue still gets flooded by fast-polling mice.

Particularly the idea that "the last good version was basically C++11" is exactly what I would expect to hear from someone who reads a few edgy articles on the internet but has no actual in-depth experience working with the language. C++14 and 17 are, for a large part, plain ergonomic upgrades over C++11, with lots of minor but impactful additions and improvements all over. I can't even think of anything in those two versions that would be sufficiently controversial to make anyone prefer C++11 over them, or call it the "last good version".

C++20 is obviously a larger step, and does include a few more controversial changes, but those are completely optional (and I don't expect many of them to be widely adopted in gamedev for a decade at least, even though for some I wish it went more quickly).