It can be implemented directly, though. Like as a site feature showing a message above the comment form, not as a bot making posts.

Ask yourself, did automod actually help that?

Honestly I think that's just a failing of community ethos. It'd be nice to bring back the expectation that people make the bare minimum attempt to check the rules of a community they're trying to participate in, and let moderators just assume that everyone has read the sidebar rules. If you haven't, and you break a rule by accident... well, tough luck, you'll get the same treatment as everyone else. Next time, read before posting.

Brave for your to assume that people read the automod comments. I quickly learned to igbore it, it was a second nature for me to scroll past it.

Than again, I never had any serious troubles with my posts or comments being moderated. Perhaps I was just not being a jerk which seems to get you very far (not already if course as some Reddits were nazis about their silly rules).