I remember even Warcraft 3 still worked that way, so the mechanism just disappered in the last 5 years or so. I don't know the technical details/reasonings behi

I remember even Warcraft 3 still worked that way, so the mechanism just disappered in the last 5 years or so. I don't know the technical details/reasonings behind that, but from a gamer perspective, here are my guesses: - The player need to be able to actually "host" the game, that means port forwarding if you're behind a NAT (which is pretty much 100% of the players). I think for Warcraft 3, if you're playing the ranked 1v1 game, both of you connect to the Battle.net host, but in order to create a custom game, you always need to enable port forwarding. The process, needless to say, is not easy for the majority of the users. - The playing experience greatly depends on the host's connection speed, and his location to the rest of the players. - Cheating. When a player acts as a central server, it's a lot easier for that player to modify the game state and force it upon everyone else.