I think there's lots of studios just as competent or more competent than Riot. They've made so few games, it's hard to compare them to other studios in that way.
I agree. I do not like Riot's "startup" approach to game design, where gameplay elements are plucked from the most popular titles on the market. The games have never felt innovative to me, they just seem like they took from everyone else and then focused on iteration so much that it gives the features and gameplay a level of polish that a lot of games don't get (especially from a esports vantage point).
The art style also feels so accessible to me that it lacks a certain soul that defines a good game.