Whys it possible to ban hover picks at all?

I've come to terms with the fact that this game is 80% kids and 10% trolls. It's easy to just mute these kids and focus on the game, communicate through pings and what-not. But these trolls are allowed to ban hovered picks. What purpose does that serve? It should completely disable the option to ban that champion. Of course, riot won't do anything about it after the game, and these trolls get to rub one out about it.

With a community this aids, we should really find more ways to prevent being fucked with.