Yes, we need to do something about this and tomhow and I are talking about it - it's not clear yet what. Raising the quality bar would likely cut down on quantity as a side effect, and that would be a nice solution. One idea that a user proposed is a review queue where experienced HN users would help new Show HN submitters craft their posts to be more interesting and fit HN's conventions more.
How about inverting the issue, highlight posts with an opt in label. e.g Show HN [NOAI]: Since it's too controversial to ban LLM posts, and would be too easy for submitters to omit an [LLM] label... Having an opt in [NOAI] label allows people to highlight their posts, and LLM posts would be easy to flag to disincentivise polluting the label. This wouldn't necessarily need to be a technical change, just an intuitive a…
Feels like effort needs to be the barrier (which unfortunately needs human review), not "AI or not". In lieu of that, 100 karma or account minimum age to post something as Show HN might be a dumb way to do it (to give you enough time to have read other people's so you understand the vibe).