In the good old days of the internet most of the online discussion happened in forums. Sure there were also the IRC and mailing lists which both still have some loyal followers around some more niche topics. But those are a bit different form of communication.
What forums were good at is capturing information. All the discussion and answers were there, available years after the original discussion to be found again when needed. And if you didn't find the answer the same place worked for asking the question too.
Of course all those forums were scattered all around the internet. Each one with just a bit different user experience and rules and the need to create yet another user account.
Of course there are many "better" platforms available today. Stack overflow and quora offer curated questions and answers, various wikis try to collect all the information in one place. And then there is Reddit, perhaps the closest thing to the forums of old, bringing every topic under a single platform unifying the mess of distinct forums. But even that often falls short to a well managed forum.
The most worrying part is that many of the communities are moving away from this form of communication completely. The discussion now happens in chat services like Discord where the information is soon lost in the stream of new messages and where it can't even be found by outsiders to begin with.