In this toxic community you will always have a big chance to run into trouble while in pre game lobby.
Like i experienced again today, 2 people flaming eachother for the role 1 wouldn't give the other while your 3e team mate purposely bans your or other team mates champion. all in all i can just take the bullet, dodge and lose 3lp for being the bigger man. But wouldn't it be useful to be able to report such people and have this kind of behavior not go unnoticed. any way of bringing these situation to light should suffice.
Hopefully a riot employee could give some feedback on this,