Too much speculation for me. There's a much simpler explanation anyway. That, and you seem to have completely forgotten just how bad Rudy was a lot of the time last season. Exciting, sure, but bad at many things.
Gobert is a confident dude, and if anything, Quin pushed that confidence up a notch when the time was right. He had to gain muscle and quit getting bullied, and quit making stupid fouls and going for pump fakes. He proved he could do that two months into the season and then Quin pushed him to use his confidence to full effect by playing his game without limitations.
As much as you think there is a what if here, Corbin just did not have that opportunity last year. If he had, there is a good likelihood Kanter gets benched sooner, and also that he isn't fired for his lack of defensive identity. It's pretty damn easy to defend the perimeter when the opposing team is scared ****less of driving on Gobert and Favors (James Harden hahalmafo).