@The-Atog-Lord Thank you for writing this. I've been basically saying this same thing for a while now. I even wrote about how Mental Misstep and Monastery Mentor should be restricted, although not in the same article.
Monastery Mentor makes every creature in the format a joke. I mean, a friend and I were brainstorming a reanimator type deck once and we were going to run Mentors just because it was cheap, broken, castable, and gave the deck a plan B against graveyard hate.
Mental Misstep has forced most blue decks into playing the card. Also it makes certain strategies much, much worse. I wonder if stuff like Elves, Goblins, Dark Ritual Storm, and more could have a shot at coming back if Misstep was restricted.
On the topic of Gush: If I asked you (or anyone) to rank the best draw spells in Vintage what would that top ten look like? In my opinion it would go like this: 1. Ancestral Recall 2 and 3: Treasure Cruise and Dig Through Time (I have a hard time deciding which is better, but I lean towards Dig being number two) 4: Gush,
Beyond that I'm not sure how I would rank them off the top of my head. Brainstorm should probably be on that list but it technically doesn't provide more cards (just insane selection).
Now if Gush is the fourth best draw spell ever printed it seems to make more sense that it got restricted for a third time .
From my article "Changes": The legacy of Gush/Mentor is kind of a strange case. Gush didn't need Mentor to be the best blue deck in the format, and apparently Monastery Mentor didn't need Gush to be the best creature in the format either. I think the case was that Gush Mentor was the perfect storm of degeneracy and that's why it was so good for so long. The best way to counteract both of the namesake cards was to make sure that individual spells were more difficult to cast. One or two Thorn of Amethyst effects negates the advantages of Gush while making Monastery Mentor much, much worse by limiting it to one (or less) trigger a turn.
Again Rich, thanks for writing this out. I appreciate reading your thoughts. I am both glad and saddened by the Gush restriction. One of my paper Vintage decks was Grixis Therapy and I spent money getting extra copies of Gush for that deck AND my Gush Oath deck. I loved playing with Gush, but it felt troubling the entire time.