Programs can’t set position or size of windows, period, at most they can ask and then hope they don’t get ignored and it’s good that way. Window management is responsibility of the compositor, not of applications.
At least KDE has support for it that’s about on X11 level, a proper-proper solution is still in the pipeline. And yes you’re seeing right it’s been there for four years.
Should all be in place. Even nvidia driver support. It’s one of the rare cases where I actually support nvidia on a technical level, that is, having explicit sync is good. I can also understand that they didn’t feel like implementing proper implicit sync (hence all the tearing etc) when it’s a technically inferior solution.
OTOH, they shouldn’t have bloody waited until now to get this through. Had they not ignored wayland for a literal decade this all could’ve been resolved before it became an issue for end-users.