xQc, TimTheTatMan, etc. Many people that have used this game as a career have left.
I think you are also incorrect. I may have exaggerated though on my part. SR will be effected due to people not being able to play certain heroes. Brig mains would drop substantially, Widow would according to forum trends, Bastion would also drop as well as Sombra. The people that play these heroes the most and have them as their best heroes will cause them to drop SR making them potentially stuck in lower elos thus making the higher elos potentially exclusive to certain universally excepted heroes like Mcree, Soldier, Orisa, Rein, etc.
Having the ability to ban a hero makes it so one tricks can potentially be useless but, as you said before, there is a pretty small chance this will happen to said one trick. Therefor, the one trick can actually keep 1 tricking except for when they are rarely banned. Besides, only cheese heroes will most likely be banned and only a small amount of 1 tricks do this to my knowledge. All this would do is potentially make those players learn more demanding heroes instead of riding on their current heroes easy but potentially effective game play.