If you have the time to play games so poorly that you go from playing in radiant games to iron, you need to get a life. 100+ games throwing for sure. Not only that, but this is a system that is in place for other games aswell, like fortnite and apex and many more. The idea is that theirs more grind to the game and that people will go back to or reach the rank they should truly be in.
The worst claim you have is MMR. Literally Asc 1 to Radiant plays as the same rank but different skill levels the first few weeks in the current system. Wouldn't be much different if it was in iron either. Not only that, but the "they'll get to radiant anyway" is legit a thing in the game as of right now when people are put back to asc1.
The idea isn't perfect and I know that, but it's a new concept that I think adds a nice twist to the game.
Also calling something the "dumbest post" and then instead of saying I've seen just saying I is a little Ironic don't you think?