1. Fun. Modern internet is boring, most blog posts are just black text on white background. Hard to remember where you read what. And you can’t really have fun without breaking some expectations.
2. Sense of community. Internet is a lonely place, and I don’t necessarily like that. I like the feeling of “right now, someone else reading the same thing as I do”. It’s human presence transferred over the network.
I understand not everybody might like it. Some people just like when things are “normal” and everything is the same. Others might not like feeling of human presence. For those, I’m not hiding my content, reader mode is one click away, I make sure it works very well.
As for “unexpectedly ended up on HN”, it’s not at all unexpected. Practically every one of my general topic articles ends up here. It’s so predictable I rely on HN to be my comment section.