r/The_Dummies is still an oddly restricted subreddit. They are able to post links visible in r/all, but you can't vote or comment without being a member.

I was looking through the reddit rules, and I couldn't find this category of private sub. Mostly I found rules for creating subs that were so private they were essentially "unlisted", but I couldn't find a qualification for a subreddit that is visible to all, but cannot be interacted with except by members.

Have I missed a rule or option? Or is the sub operating in a way that is blatantly against the rules?