All rollback fighting games are pure p2p, there is no server for gameplay, just matchmaking and leaderboards. I'm not sure if what you would describe would work

All rollback fighting games are pure p2p, there is no server for gameplay, just matchmaking and leaderboards. I'm not sure if what you would describe would work, it would at minimum double the ping between the two players, and in games that set variable rollback windows based on ping that delay may grow exponentially until a disconnect/desync. Also I think no one has attempted to cheat like this because it's much easier to cheat with a program that 'reacts' to graphical cues (such auto-block bots are pretty common in the most recent Tekken and Street Fighter entries). There are some very rare moves that are impossible for a program to react to like this (usually '0-frame grabs') which hit on the exact frame the input is entered, I'm not sure what if anything the current cheaters do about those.