The thing is that desyncs really shouldn't happen. Hopefully the cause is just due to lost packets and not bad programming. If they do appear, then that means that there is a different between what the players have in their games, while everyone should actually have the same exact data. Once a desync happens, things will continue to stay different across your games, so it is kinda' one of those things that you see and then need to start a new game.

If a desync occurs, the match is already over. You've likely lost some game data somewhere or one of the players has intentionally altered their gamestate via hacks, etc. As such you're not even playing the same game as everyone else anymore, and what happens on one player's screen may happen differently on another's. As a game progresses past the initial desync things will diverge more and more as the commands are issued based on wrong locations, random number calls return different results, etc.

An option to quit the game on the desync window would be convenient, considering everyone will ultimately quit when the message appears.