> I have no idea why this changed in more recent games.

I thought the reasons were basically:

(a) accessibility - running a game server requires some technical knowledge, and if you're doing it from home, possibly changes to your network (and home connections likely won't have as good of routing)

(b) cheat detection - since the server is run by the game developers, it's easier to find misbehaving clients and ban them across all servers.

(c) DRM - it's harder to crack a game that has to sign-in to cloud servers.