I've been writing open source code for 30 years. I can count on 1 hand the number of times a random 3rd party PR contributed value to the project. The main contributions of the community are usually debugging and feedback. While it does happen that a good contribution comes from the community, the main values from opening code are increased user trust and identifying bugs. Almost every single open source project has a small number of devs who write almost all the code. The reasons for this are always about code quality. The idea that "the community" writes any open source projects is just fantasy. So refusing AI slop is just continuing on with these same policies that have worked for decades.
I dunno, I added a major feature to a project I had never interacted with before because I needed the functionality at work. I even used AI to help me (and spent a lot of time cleaning it up, as I didn't want to submit something shameful, but I needed the AI to implement a particular section that was on the edge of my understanding).
The code got accepted and is now released.
I imagine if the project maintainers were curmudgeons like OP, the rest of the community would never benefit from the work I did, and I'd have to keep it as an internal fork.
Am I really that exceptional, where these contributors can count on 1 hand the number of times people like me contributed something useful? I guess it probably depends on the project.