Subreddits encourage group think, discrimination, and dilution
HN is an inspiration for how to run a platform and have it be extremely engaging. To tell you the truth I still don’t get why people are so obsessed with “Reddit” and not “HN” alternatives.
But I can see how HN is also in a unique position where a lot of the site users remember the early days of the web, back when things were a lot simpler, and individual focus was not diluted in 100 different directions.
Good discussion requires opinions that are both diverse in perspective and well reasoned – and a bit of intellectual curiosity and open-mindedness doesn't hurt either.
Something I think HN does right is that it doesn't segment its community and it doesn't reward or emphasis upvotes / downvotes which makes the community much less prone to say things solely for social respect, and therefore less prone to group think.
When I go to HN I never know what I'm going to find. It could be tech, business, economics, history, or just some interesting event happening in the news. HN forces its users to be exposed to a diverse range of content, and because the only post requirement here is that the content is intellectually interesting it tends to naturally attract people who are intellectually curious.
On HN I find myself in reading and participating in discussions about topics that I'd never ordinarily seek out and I think this is what encourages the diversity in perspectives shared here.
Think of it this way, on Reddit if you want to discuss React you'd first have to seek out a community which is cares enough about React to talk about it. And often that community will be solely focused on React and therefore generally enthusiasts of it. Now imagine someone shares a post about React Hooks, how many people do you think will be giving critical opinions of React Hooks in that comment thread? And if someone is being critical of them how might a community of React enthusiasts response to that person?
Compare that to a thread you might find about React Hooks on HN. You'll have people who love them, people who hate them, people who have no idea how they work, maybe even a couple of people who are completely nontechnical who just want to share their thoughts about something their developer colleagues said about migrating to React Hooks.
This is what makes HN so awesome in my opinion – there's no gimmicks, just a community of intellectually curious people discussing things they find intellectually interesting.
Tildes has a curated selection of topics: <https://tildes.net>
Lobste.rs is far more similar to HN in overall dynamic ... and includes tags: <https://lobste.rs/>
HN has long held out against groups, tags, or topics in the interests of providing a single unified community (see: <https://news.ycombinator.com/item?id=11843220>, <https://news.ycombinator.com/item?id=23716718>, and <https://news.ycombinator.com/item?id=23308098> for example).
HN does have an excellent site search (through Algolia) which may serve some of your interests. There are also curated collections of posts available under the "Lists" link (<https://news.ycombinator.com/lists>) including Best, Invited, and 2nd Chance, which tend to serve threads of better-than-average quality.
When using search, it's often helpful to search recent comments rather than posts as the former tend to be a larger and richer target offering more hits, as compared with the often vague and nondescriptive 80-characters of a post title itself.