> It's common for shooters to want to guarantee that if it looks like you shot the other player on your screen, the game will react as if you shot the other player, even if the server would have considered it a miss due to timing differences. Those things can really only be done by trusting the client not to lie, which means verifying that the client hasn't been tampered with.

Why does server-authoritative backwards reconciliation require trusting the client not to lie? The server keeps a history of the past N states and client claims to hits are verified by the server using that history. A client could lie and say it made a hit in one of those prior states (but not an state the client invented whole cloth.) But if the client is doing that then from the server's perspective that player is lagging and backwards reconciliation makes lagging players easier for other players to hit.

Obviously if you're doing client-authoritative unlagging then you need anticheat, but AFAIK competitive shooters have used server authoritative backwards reconciliation ever since the early 00s.