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 karma).
The net result is that these rules ensure that much greater proportion of new accounts come from bad actors - who else would jump through hoops just to participate on a web forum?