Slop ambience just sure sounds to me like HN is banning a prose style. I guess I just think that if this is how the rule will be enforced, that is how it should be written.

Home can be sure the LLM is modifying just the prose style? Moreover, prose style is one of signal that convey information about what you are trying to transmit (unlike code, which is totally debatable if it should have meaning on its own).

HN already does a decent amount of content-policing, which helps keep the discussion higher quality. I don't see a huge diversion here from the usual moderation.