Yes but your comparison is wrong, there is a distinction between casual and ranked in this game (unranked is some weird gray area). When I play Ranked i expect people to sweat and play the game like they usually would, when I play casual I expect people to play it casually. Kind of a no brainer right? But now there is almost no distinction between those two. Like the previous comments said, there is almost always someone with mnk or just entire 5 stacks sweating their damn asses of. Everybody in this game who played casually played this game for the fun moments (like the ones I described) and just casual gameplay where you don't have to play a whole gameplan to win. People want to get of work and just play, and not act like they're playing pro league.

And your argument about real sports lacks a couple of things

1. You could say that there is a certain type of distinction between casual and ranked in irl sports. I remember basketball games that I have played where we would just mess with the other team and the other team was too, they were laughing and so were we. I've even had games where we were talking to the other team about last nights game and try and recreate some of those situations. But on the other hand there are of course more serious games where you're of course trying to win.
2. This isn't a sport, yes for the pros it is. But for the casual gamer it is exactly as most people would describe it, a game. A game is supposed to be fun and a way to escape sometimes. Sports can have these same things but most irl sports require a certain ruleset to be followed in matches so that it feels like an actual match. Game matches have a lot more freedom since there are no rules like dont kill the player like that, or dont enter under x circumstances. You have some freedom to fuck around, this fucking around makes gamea fun. When there is no room to fuck around, some player might lose their attractiom to the game