there are other forms of filtering/ rate limiting like by reputation, HN does this already to some extent for new users < 500 .

Recency of reputation changes can be factors so historical accounts don't accrue a lot of value for bots to buy.

We will downvote spam or low quality content anyway . Accounts (users or bots) with poor rep can be more harshly restricted.

Ultimately does it matter if a human is actually posting if the post is insightful / useful ?