Talking with actual workers in a field is super valuable...I think that's what makes HN great - most of us work in tech.
With Reddit, you get tons of 'oh, I like guitars, I'll join that' people giving advice instead of say, professional musicians or luthiers.
Note: I didn't mean to insult r/guitars, I've never been, just used it as an example.
When I used to use Reddit heavily, I had 5 different accounts, easily managed by the app and RES on Firefox.
One was for Physics, Astronomy, and Math (earlier in life), one was for books subs only (suggestmeabook, books, etc.), one was for CS, programming, language subs, and so on, one was for everything else- i.e. memes, short videos, etc, and another one was for skills I was learning- piano, drawing, etc.
This was, I had everything managed.
Of course the subreddit still needs to be focused on a specific topic
In terms of quality, Reddit mods are hugely important. I was a mod for my city’s sub, and it was a constant effort to filter out the low-quality or toxic content.
/r/PersonalFinance for not-super-technical-finanace. I'm more familiar with PersonalFinanceCanada which has single-handeldy taught me how to think about money and finance. Can definitely get a bit toxic sometimes.
/r/Guitar is surprisingly small but still fun, and /r/Frugal is another favourite of mine. I also frequent the many FIRE subreddits but I don't think those are as popular as other forums about FIRE.
In a similar vein, Stack Exchange can be VERY interesting. I often casually sift through WorkplaceSE and TravelSE, though I supposed that is more entertainment than educational.