This is what most people seem to miss in this HN thread. Go look at the average 'large' subreddit, and I'm talking about the ones where personal anecdotes are expected. You'll tend to have some top level posts that are decent, and generally longer post. You'll have hundreds of posts that are memes, crap like "5 out of 7, perfect", subarguments that go off topic, and plenty of bots posting comments from other threads. The format the /r/science requires is the antithesis of 99% of the rest of reddit.

This leads to moderation fatigue. You have lots of stuff that should be summarily executed and takes up tons of your time. Then you have the minority of posts that require some thought on if it's just a controversial post, or that guy that just keeps making accounts and being an intentional malicious troll. But, you don't have any time to think on these post because another 3 crap posts ended up in the moderation queue in the 3 seconds you're looking at the first one. Eventually people get to the point that if a post ends up in the moderation queue it just gets blocked, which then trolls use to flag just about everything. It's a messy situation when you're asking volunteers to do this.

Building a culture of moderation that promotes transparency and not using mod tools as your pet ideological argument winning device is not a lot to ask.

There seems to be zero ethical guidelines / pressure / consequences for any of this stuff.

Of course the problem is hard but I've seen tons of high quality, on-topic comments with 500+ upvotes get removed because the mods obviously disagreed with it. The commenter won't even know it's gone and 99% of visitors will not realize how thoroughly editorialized the entire conversation threads are.

I seriously recommend picking any even slightly controversial r/science post and look at the comments being removed. It's not just memes and trolling.