This is something that has been pissing me off in ranked lately. I come into the lobby and say my preferred roll and say don't ban x champ because I would like to play them. Almost every single game my own teammate banns them first. Seriously wtf?! Don't they want to win, when I say I have a good record with x champ, then you ban them, that just hurt your odds of winning as well. Why do people do this?
Easy,
People are assholes
Honestly I wish I could say I was kidding but It boils down to the fact that some people just like making life difficult. It's a side effect of internet anonymity. When people dont have to show who they really are and can hide behind a veil of anonymity it tends to bring out the worst in people.
I would just stop telling people who im gonna pick
There are only 2 reasons really.
I recommend you never main the champ who is a high pick ban, eg 
Call your role but don't say who you're good at :^)
if you play a champ like reksai, cass, zed, ahri, pretty much anoyone op and you aren't second pick or trading don't expect to get your champ. Now if you say please don't ban urgot or galio, that is a different story.
