A large enough difference in degree becomes a difference in kind. Chat bots have vastly inflated the amount of shitty PRs, to the degree that it needs different solutions to manage.

Exactly. We never had a problem with spammy PRs before. Even at the height of Hacktoberfest, the vast majority were painfully obvious and confined to documentation. It was easy and obvious to reject those. But LLMs have really changed the game, and this policy was explicitly prompted by a number of big PRs that were obviously purely vibe-coded and we felt we really needed to get a defined policy out that we could point to and say "no, this is why we're rejecting this".