It’s not just popular projects. On a small utility I have I received a PR that was more lines than the project had. I’m happy to be a good maintainer, but reviewing something that’s effectively an AI rewrite isn’t something I care to review and since I can’t vet it, can’t blindly accept it.
I’m sure it’s all over, I was assuming the smaller projects could deal with the handful of contributions.
Something like a big emulator is very complex and has a LOT of motivated users who aren’t going to be able to make quality submissions.
So they get it in volume where it may be nearly impossible to deal with.