Reddit and HN aren't forums, they're factories for quick takes and reactions (and yes this is one of them). It's a transitory experience.
The good old "crappy" forum format isn't gamified with upvotes and often have long-running, slow-burn threads that go on for months or years. Even once popular, high-traffic forums such as SomethingAwful had a different pacing and community feel to them. It's like a pub with its locals and regulars, but where new faces sometimes pop in.
With that said, there are still plenty of "crappy" forums around, typically at least one for every special interest or hobby imaginable.
Bogleheads (made up of investors who follow Bogle's indexing philosophy) recently had a thread about the decline in traffic to the forum, which some people attributed to AI. (https://www.bogleheads.org/forum/viewtopic.php?t=470287&star...)
It wasn't just "Why bother reading a thread if I can find the answer quickly using AI search/Gemini/Claude/ChatGPT?" There's also the Cloudflare effect, which stopped AI crawlers and bots from posting slop, but also led to some collateral damage ... BH content is less likely to be indexed, and some users will bounce from Cloudflare prompts.
In addition to the "gamified" aspect, the votes allow special interests to trivially control the perceived public opinion on an extremely broad scale. Opinions with downvotes are perceived as unpopular, and this has a chilling effect on free discussion.
A real person who expresses an idea and gets downvoted by a passing Russian propaganda bot may see the vote (and subsequent Reddit weighting algorithm fuckery that turns the one well-timed vote into 10 votes, which a lot of people aren't aware of) and feel ridiculed, which will discourage that person from expressing the same idea in the future.
Other people who see the same post with X downvotes will take note that that idea is unpopular, and may unconsciously realign their own views on the idea to fit what appears to be the prevailing opinion.
And of course crappy old forums have the other advantage of not having any single standard registration process or API that can be exploited by bots en masse. That's not going to keep them out entirely, but it drastically increases the logistical cost.
The 'like' counts in places like YouTube and Instagram comments have made clear to me the idea of tyranny of the majority.
Could you perhaps, suggest an index directory that can lead to quality board discoveries?
In my experience, finding a quality board has always been topic focused. I.e. if you have a Toyota Corolla and want to communicate about that, just look for Corolla forums, and it'll quickly become obvious if one is lively / your vibe.