I mean there is Kaze Emanuar who has rewritten the decompiled source code for Mario 64 and getting it to run up to 60fps on a real n64 with his custom levels having graphics bordering on GameCube level. Tons of really cool optimizations went in and If I understand correctly everything between but not including 30fps and 60fps looks like shit on real hardware.

If one person can do this kind of optimization AAA devs should be able to as well but I guess shareholders something something... Really though there is no excuse for anything looking worse than several console generations ago to not run at least 60 and yet here we are.