Deterministic multiplayer has an assortment of cheating problems that weren't really a big deal in the early days of online multiplayer, but certainly are now,

Deterministic multiplayer has an assortment of cheating problems that weren't really a big deal in the early days of online multiplayer, but certainly are now, in the days of ranking systems and very competitive gaming. The obvious one is that the client knows where everything is on the map, even when hidden by fog-of-war - so client-side hacks can reveal that. A hacked client can easily desync the game too, or stall it and cause it to time out if the player is losing.