[ACS_Solver]

The super-long threads are a matter of forum policy. Some forums have a rule that everything about a single subject goes into one thread, which can then grow to be enormous, other forums encouraged more threads. But even with the hard to read megathreads, I think the downsides were easily compensated by the fact that the information would still be there a year later and even ten years later.

I've never liked voting systems on forums because they elevate popular content to the top, which is not necessarily the same as the best content. One of the major advantages of forums in my opinion is the opposite, that forums are a good place for niche discussions as well. Some obscure technical detail that only a few people are deeply interested in can be discussed well on a forum, better than on a platform with upvotes where it'd fail to get the critical mass of points. And of course sensible moderation is the cornerstone of any good forum.

The best system I've seen in online communities is a forum for discussion and a wiki for reference. For a while there, before most forums died but after the early wave of forums, there were quite a few communities that ran a forum together with a Mediawiki install. I still find it vastly superior even to well-maintained subreddits. Some subreddit communities have good wikis, but they're very feature-limited, and no matter how good a subreddit is the discussions suffer from the platform's focus on fast discussions and a terrible search.