Because it doesn’t seem to matter currently if you play ranked games or casual games, the general experience tends to be the same. But one has numbers and things to go with it. You still get people playing to win in casual games and you get people dicking around having fun in ranked games, and the ranks don’t necessarily indicate how they play as a team and a whole bunch of other things that make it less than ideal.
I remember those times. They were awful. I had no fun if the people I started the match with weren’t the same I ended it with. What was the point? It’s not fun if I can’t even tell if I’m getting better at the game. I didn’t need to be the best Counter-Strike player, but I wanted to play actual Counter-Strike.
However, while this isn’t necessarily mutually exclusive, those games that let you run your own servers will actually survive to be seen by future generations, unlike just about every game with matchmaking these days that won’t let you run the game in LAN or on a private server. It’s possible to have both, but devs don’t want to.