Does it need to be a "direct" benefit? I think sometimes the things we do out of our own volition shape ourselves not only directly but also indirectly.

As a personal example, I have noticed how my way of discussing heated topics has changed based on discourse I have seen here.

And this would not have happened if I didn't invest time similar to yourself.

Yes in your case you identified a specific way to improve your communication skills by immersing yourself in the HN environment.

This is a hit or miss though, because you either identify specific ways to improve or not, and you may or may not actually improve those identified skills by reading trough the comments (and not taking action).

If improvement is the goal, then there are more efficient ways to eg. learn better ways to discuss heated topics (like reading a specific book on the topic, or attending a "Nonviolent Communication" workshop).

The more I think about this the more HN only seems like a place to get a specific flavour of entertainment (which I personally like), but nothing more.