Honestly, it really depends.
If you have no way out of a league, then I could see it as a bad thing. Obviously, a league with an inactive or hostile playerbase is not one most would want to be with, and if you had no way out, promotions aside, then I could see this as a very bad thing. Also, I don't think it would mean too much if they didn't have a way to really communicate outside the gameplay.
If you could change leagues, even with a cooldown, I think that the system has merit being insular. I like the idea that sub-communities can exist inside a game. For example, I like how Dark Souls has a thriving Sun Bro community, or for a league related example, I like how players of a certain class or champion come together on the forum to discuss and enjoy various aspects of the game, and have different ideas on how to make it better. They may not always have nice things to say, but I like how they can come together to have an understanding with one another.
So to sum up my answer, if the League system was more flexible, then yes.