FFS... This is one of the things, as a fan of an neutral program, that pisses me off about the Michigan fans trying to constantly diminish this...
I don't care if Signgate wasn't particularly effective. That isn't the goddamned point. The point is that it was one of the most egregious and unconscionable cheating scandals I've ever seen. I put it akin to point shaving or paying off referees, but often those things can be coordinated by individual players or people outside the program, whereas this was institutionalized cheating... With literal receipts, submitted as part of expense reports! Bagmen and recruiting violations are one thing, but this was one of those that was targeting the sanctity of the actual on-the-field competition (much like point shaving or paying off referees).
Trying to defend this is like terrorists saying "yeah, we intended to corrupt the NYC water supply with Ebola and kill several million people, but we screwed up the recipe and all we did was give a couple thousand people diarrhea." And then acting like they should be excused because they failed to achieve their intent.
If your defense of cheating is "while, we were still good even when we stopped cheating, so our cheating didn't really matter!", you clearly don't see things the way the rest of college football sees them.