This is it, right here. Good games are fun to lose as well. Otherwise it's just a competition where you occasionally beat people and feel amazing about yourself, or lose to people and feel terrible. The variable reward system in ranked LoL messes with our brains, gambling machines and pay-to-win games have exploited this for years.

League, at least for me, didn't seem like a fun game (at least in like 2010 or whatever it was?). Most of the time was hitting hapless minions and waiting for some timer to finish so you could finally fight a human or go jungle/dragon or whatever it was. But that would be over in a few seconds and then back to grinding away at some shitty NPCs. Maybe some people enjoy the actual gameplay enough but 99% of my LoL friends played either for social purposes or were hyper competitive.

I found SC2 way more fun, pretty much every game was fun unless the opponent themselves did something boring like cannon rushing. I would routinely come up with interesting builds/strategies and test them out on people (fun to figure out if it worked or not). Mass marines, weird timing attacks, anti-meta. I didn't see that flexibility in LoL. The mechanics (for me) were far more involved and enjoyable anyway but that's my shitty opinion.