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 said something similar in another reply, but I can’t think of any games where winning/losing is possible but doesn’t change my enjoyment. Even elden ring invasions feel better if you win the encounter.
The only thing that could come close is an encounter like that or in something like DMZ where you can talk it out and join forces, but maybe that’s just another form of winning.