In ranked games (or games where the objective of winning is more important than just having fun) the lobby system does work better, because you're not really looking for community in that case. If modern games like Overwatch had both systems (join a server with regulars and make friends as 'quick play'; matchmaking for competitive), I think things would be better.
The only time I get properly annoyed in a game is when team sizes are fixed, and people are trolling or not pulling their weight. But on a server where anyone can join and you're chatting between spawns? That's fun. Sure, you care about the map objectives, it's not serious. If you lose you just stick around for the next map in the server's rotation and play more.
afaik you can actually make lobbies in OW (game browser > create).
>I suppose I had in mind more casual games, that is, no fixed size on teams (anyone can just join and play so long as you're not over the server-set limit of players), and unranked.
This is my problem with survival games like Rust or DayZ. Really good concept, can be played casually, but somehow ends up ultra competitive if you play with randoms :D