The Rivals of Aether dev has talked about the difficulties of rollback
Rivals of Aether is finally coming to Switch on 9/24. What took us so long to get here?
fornace.medium.com
Not only him. I remember reading something where the switch is not powerful enough to run a game like smash and rollback. This is a great oversimpflication, but smash runs at 60 frames per second. Based on how fast this game is, to able to rollback an additional 7 frames, the CPU would need to be able to run the same game at 480 frames per second. This is a great achievement for a modern game on modern hardware, and requires a lot of special engineering. For the humble cpus on switch, running a far more busy fighting game like smash, is a challenge that has simply not been done. Games like rivals is farrrr less graphically intense busier game. Would be more tamed to handle it i would say.
The example i like to give is camera effects. you have all those zoom effects for example when a character dies and character specials and hits. Rolling back any sort of camera effect would be awful.
So all the zoom effects have to re-tuned around your rollback delay, and even normal camera
behaviour would have to be rewritten to not jump around with the game state changes.
Sound effects also have to get a massive amount of attention to be polished- cutting off
and jumping into sounds effects midframe could be rel jarring and bad.
Particles are also often a problem, since particle systems often have non-deterministic components in their libraries.
This is even getting into the wierd game design decisions. MK guys actually refused to rollback
game-ending hits as policy, due to how aggravating that would be.
This is all I remember. So people who loveeeeee to say "just add rollback" and how Nintendo/Namco is lazy to add rollback don't know the hell they saying.