They didn't take into account the long-run impacts of the changes on future development, etc.

I recommend reading the explanation given by one of the Zig devs, as it's a very clear and solid one.

This is the most common issue I see with LLM authored PRs. Yes it does fix the issue _right now_ but as a maintainer I need to consider how it affects the project in the future. But “contributors” get mad if you reject for those reasons. So I can understand having a blanket policy.