Why Ban Hover Champion?

I hate it when my team ban the champion that I hover, intentional or not. What is the point of indicating what champion you want to play when your team mate are just going to ban that champion. Sometimes it is a accident and i don't mind but most of the time your own team ban the champion you want you to play for some reason. I thought you have team mate to help you not bring you down. Please do something about this matter riot.