Reddit has tried this approach and, IMO, it's failed. A new human user will spend actual time creating a thoughtful and helpful post, only to be greeted by "sorry, your post has been removed by automod because you don't meet criteria". They get disheartened and walk away forever. The spammers, on the other hand, know how the rules work and so will just build their bots to work around this (waiting 30days, farming kar…
It failed on Reddit because Reddit is maintained by a bunch of volunteers to whom Reddit provides woefully, woefully, horrifically underdeveloped tooling to automate their communities in a more nuanced way. Hacker News has three advantages. First, it is moderated by the same people who build the tooling, so the incentives are aligned. Second, it is an enormous source of soft power for a venture capital firm with the…
And on top of that, some of said "volunteers" are power-hungry, petty, useless fucking morons. Especially the large subreddits tend to be run by people I wouldn't trust to boil some pasta without triggering a fire alert, and yes I know people who manage that.