> Often they are very subtle errors based in very subtle misunderstandings.

I'd like to address this specifically. Introducing a very subtle bug can be an adversarial move, right? Say I want to introduce an exploit into a project, I can try to do that. And it is a risk in any open source project where contributions come from "random people on the Internet".

Now my question: as a maintainer, is it better for me to try to convince myself that all those contributions I receive from random people are well intentioned (and maybe miss subtle bugs that were introduced on purpose), or is it better to have an AI replace those contributors?

I don't have an answer, but I think it is an interesting question. As a maintainer, my bottleneck has generally been more around reproducing, understanding the bug and testing. Less around producing the code. And an AI can produce the code I ask it to produce, copying my style, and I can ask it to start over as often as I want.