Why no official role selection ?

Why do we not get to officially chose our lanes/roles so that other players can clearly see them. Too many times lately, character selection starts, people start calling top/bottom/mid etc. and then there are arguments because someone connected to the chat after someone else already called a lane, and wants that lane also. Just now, i connected to chat in a game, my name was listed as first in room, and 4 others joined. I then called ADC and others called theres, then in the 10 second countdown one other guy tells me to change and i am like what ? then its too late. In game now hes bombarding me with grief for not changing characters and he called bottom, we lost badly, and then in the post game chat another team member came out and said he called bottom first, yet i didnt see it on my chat and they waited til way late to say anything. So why not have a dropdown with all the possible roles, have it clearly displayed next to your name and a number indicating the sequence of players that selected the role, i.e. i selected bottom first, i am BOT1. Just seems too many arguments in chat pre game on who chose what first.