[dredmorbius]

Keep in mind this is either a subreddit or Automoderator setting.

Subs can limit posts to users with some minimal karma or age. Typically this still permits comment, though harvesting comment karma is then incentivised.

Automoderator, a rule-driven automated moderation tool, can actively interact with posts and comments based on various criteria, including automatically holding or removing posts or comments, messaging submitters, and other actions. This is heavily used on highly-active subs, and pretty well documented.