I'm not sure that's true, if you look back at what was going on at the time, it's eerily similar to the Dream fandom's activites. You had all the people shipping PewDiePie, Markiplier, Jacksepticeye, making similar looking artwork of them to what you see today for the Dream people, and writing all the fanfictions, and usually the people involved with this stuff are girls.
Maybe you could say there were multiple offshoots of the fandom, with one consisting of cringy kids in YouTube comments who mostly happen to be boys, but the former was certainly significant. Though, compared to the Dream fandom it at least appeared more tame, probably because there were just less people in general watching YouTube at the time, and the climate was a bit different, so you wouldn't have as much open crazy weirdos, woke activism virtue signaling, etc.