Sure it would. No matter how many people see, say, Shpongle on their timeline, they're never going to be mainstream. No one is going to be talking about 空夜coo:ya in the same conversation as Taylor Swift or Bruno Mars. Being slightly more visible in the algorithm for a brief period isn't going mainstream.

And even if that were the case, again, so what? If Youtube makes good non-mainstream music more popular, that's still a good thing. That's exactly what one should want a recommendation algorithm to do.

I'm trying to see the problem here and I can't.