Another downside of current gen matchmaking is just how SHORT games are. Back when I played Halo 1 pc's multiplayer, you could watch a single Blood Gulch CTF game go on for an entire WEEK before one team got the 7 captures required to win on that server. It created a really interesting dynamic where attempts at the flag were each unique events, requiring planning, preparation, camaraderie and teamwork in a game without voice chat. You could leave a server to go to bed, and wake up the next day, hopping back on and see the same people on the same teams still going at it. It was much more IRC-like in feeling

People built communities by just being on the same server often. Friendships were made, guilds too. But now all you have is 12 other little kids all free-for-alling shotguns for a brief 5 minute instant gratification fest

That feel still exists in certain communities, such as Insurgency and Arma III, which are both great on Linux.

Games like League of Legends support custom games, but I don't get the impression that they are used much and I don't know if there are persistent servers there, so you don't get to go hangout with the same gang/community at will.

I still play a short list of favorite servers in BF4. This is a game from just a couple of years ago. Are you saying some newer games only have random matchmaking and no joining a favorite server?