Top players are going to do it if it is needed or not. You can not force diversity in a game. All you will end up doing is making it bland, people lose interest and the game dies. The game graveyard is full of games where the devs caved in to the whining of players who are unable to see the big picture.
Look at the top 100. Guin isn’t the only hero that is over represented. All will fade out as new hero’s come out even if they represent just a small fraction of improvement over the current kings. There will eventually be a better tank and they will be used just as much if not more than Guin. Your cry for diversity will be for nothing. You will just be changing out one for another
And let’s not forget that the top 100 are not there because of their defense team. It’s not like they pulled Guin, stuck her on D and woke up that morning at rank 12. I’d imagine other hero’s would be receiving more grief from players if they were able to witness the offensive hero’s used against them. Imagine the ire of you had to watch the synergies of Turlock or Wu constantly…but no. That’s out of sight, out of mind so the FOTM gets your ire. You see the representation and you foolishly assume that’s what is broken.