The problems would only get exacerbated if more of them migrate over here, that’s the issue.
I doubt that it would make Lemmy significantly worse. I’ve already had to block nearly a hundred lemmy communities for containing the “mindless trash” that is abundant on reddit. The reality is that most people aren’t smart and don’t want to browse and participate in intellectual content. They want to mindlessly scroll through endless memes. I have not observed that people on lemmy are overall more intelligent than people on reddit.