You make it sound like this is a hard problem that studios don't know how to solve, but it's been solved for decades. There's still a bunch of third-party Quake III Arena servers you can play on, for example.
Implementation aside, I think it’s primarily a money thing—the studios don’t care about this because the numbers say they shouldn’t.
Online-matchmaking becoming more and more centralized really made this starting to go away... It has both good and bad sides. One is much larger player pool and automated matchmaking. Other side is losing communities and more custom servers with custom maps...