I'm not saying it's bad, or criticizing anyone. I mean it does what it does, and it works, and people like it. But no one should care what technology they're using because there's just nothing impressive going on from a technical perspective.
I've been writing web apps since 1998. Just today I implemented a similar tree view, with ability to create, edit, rename, move files and folders in a TypeScript react web app, and my app that I wrote today is a vastly more sophisticated GUI than Hacker News. lol.
The frontend of HN doesn't need to be complex and I'd even argue that it's better for being simple as it's then easier to parse, takes less effort from the client to render, certainly less battery on mobile, and so on. Web applications don't _need_ to be more complex than the problem at hand where the frontend itself is just enough of to display content in a comfortable enough format for human consumption.
Unrelated to the topic but related to the thread: if you edit a message then please keep the original message around to keep context for others that read this thread if that edit would change how the message was interpreted at the time of the reply. Non-functional edits (e.g spelling corrections) are fine without notice.
If you want to know what stuff I'm impressed by it's things like Mastodon, Nostr apps, and stuff that does more than edit a simple content tree of nothing but plain text. We can't even upload images. Can't do markdown. lol. It's definitely a "Less is More" app, from two decades ago. Just agree to agree with me on that. It's not an insult to them. It's just an observation.