Wow, that's an interesting sub. They've formalized a lot of the HN community standards into hard rules, and brutally enforce them. For example, this[1] post has 36 comments, and 10 of them were removed for either not being substantive, not backing up statements of fact with a source, or some other reason, and another is reminder of a top level comment to include sources.
I'm not sure they haven't gone too far to some degree here, especially since the offending comments were deleted, not just hidden, so it's hard to see whether the mods are justified or not in all cases.
I subbed in any case, so I guess I'll get a chance to see more to make a more informed decision.
1: https://www.reddit.com/r/NeutralPolitics/comments/81f8wf/are...