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 feel like competitive gameplay could be fun for everyone but the space would have to be well-moderated but not sanitized which, IMO, is hard to do with an online platform.
We used to have hella fun playing Mario Kart on N64 with the neighbors when we were kids but it isn’t like problems didn’t occur, they just got resolved quicker and we learned that it’s best to be(e) nice if we want to have fun.
In an online game, you’re probably talking shit for weeks before you get forcibly removed from the game for any length of time.
Edit: to add onto this, it isn’t like you’re seeing most of the people you play with the next day at work or school so there really isn’t much incentive to involve yourself in the game’s community.