If you think that's mind-blowing, imagine this:
Imagine a game where there are so many ways to play, but there is clearly a dominant play style, to the point where, at higher levels of play, you have to have a certain composition in order to win.
Now, take all of that, and imagine that there are only 6 slots to fill on a team, and dozens of characters to choose from, yet every single game at high level features the exact same team composition.
Mind-blowing. Right?