> it could have been rewritten, rewriting PRs is cheap today

Rewriting PRs with LLMs is cheap, but often the output is no better than the previous revision (fixing one issue only to cause another one is very common IME). And reviewing each revision of the PR is not cheap.

I've had good experiences with people submitting AI generated PRs who then actually take the time to understand what's going on and fix issues (either by hand or with a targeted LLM generated fix) that are brought up in review. But it's incredibly frustrating when you spend an hour reviewing something only to have someone throw your review comments directly back at the LLM and have it generate something new that requires another hour of review.