Serious question - what does detaching a thread in HN do? Because I still see it show up in the main comment section.

Detaching a comment means removing it from its original parent (the comment it replied to) and making it a top-level comment of the thread instead. Usually, but not always, we do that in order to mark it off topic so it can rank lower on the page.

More like: "We detached this subthread which spawned the most interesting discussion in this comment tree because we are addicted to controlling the conversation and we want things to conform to our social justice agenda - nothing controversial is allowed here."

Your moderating produces negative value.

I'm glad you found it interesting. As you can see, it's still here to be enjoyed.

The problem is that generic topics like "do we have free will" frequently balloon into large discussions that crowd out the more specific topic at hand. If we didn't moderate HN this way, HN threads would consist mostly of the same generic discussions repeated over and over. I'm pretty sure the community wouldn't agree that it "produces negative value" to prevent that from happening, even though we don't always make the right calls.