Based in summaries, it seems like a lot of it is. Some of it, like pairing fic I'm more familiar with, is one-sided or PG fluff. I think it's become common because it wouldn't be hard to take an OC story or Mary Sue and replace with Y/N, changing little else. That it's a way to get readers and at the same time, not get "flamed" for old skool wish fulfillment.

Since I write smut that wouldn't be a deterrent anyway. ;)