@wappla I don't know which is better: your quality as a writer or your knowledge and analysis of Vintage. I have to agree with you or simply shut up and learn from someone who has given me more than one awesome advice. However I still have to disagree on one thing. Maybe even two. And I assume that surely I'm wrong.
Black is not on top, but demonic and vampiric (and DP) have something that blue currently does not have. They can find ANYTHING. It means that providing your opponent does not have countermagic, or that you can dodge it, you can win with your empty hand against a controlling position on the spot. Tutor for ancestral and recover. Tutor for vault and play infinite turns. Play it for removal and recover that position. Damn, fetch y.will and go crazy. I know far less than you to give some kind of lesson about card advantage vs card quality. However, if you can avoid the "fair" card advantage combat where mentor shines, black quality can take a win using less resources, but critical ones.
What brings me to "bad removal". Engieered plague, virulent plague, illness in the ranks, sulfur elemental... they are not bad answers to mentor. They can be bad answers in certain decks. Are you going to win mentor by playing one of them and without doing anything else? Of course not! What if I also add a canonist to battlefield? Then mentor is not such a terrible monster. What if I put a spirit of the labyrinth or chains? Or maybe my plan if to play vault+key using 2 full turns. Perhaps I have a jace happy to bounce mentor as much as 3 turns, dying in the process but causing you to waste 6WWW in the meaning. If I play baleful strix and draw illness in the ranks, I have answered your mentor for 3 mana, and I have time to prepare my combo. I have to confess that I found those answers plain bad for decks equal or less broken than mentor, but often you only need time to win, and those cards give time.
Just as a bonus track: is mentor less oppresive than other decks? Clearly it has not an explossive start as other decks. It, in fact, allows the opponent to survive at least few turns, and to play spells. But mentor is implacable when paired with gush. There are several different configurations that take profit from these 2 monsters, capable to create such a big advantage that gives mentor the edge in most long games, providing its counterwall/silver bullets allow staying in the game. There are times when you have lost by turn 3, even if the game is closed several turns later. Often that sensation of fairness is just an illusion. Mentor+gush is not fair. We can join them or play against them, but they cannot be ignored. Mentor is now the tier 1, and not by chance.