Although, this could be considered a good thing. It means that there is variety out there for specific subjects/areas. We all can't please everybody all the time. So, some people don't mix well with others. So having several forums dedicated to a specific topic means less toxic behavior in the forum. Like-minded folks attract to each other.
I personally seeing forums may be coming back mostly in part because of the censorship that seems to be happening on Social Media. That and the overwhelming advertising that occurs on most social media platforms. People are constantly complaining about posts being removed because of "content violations", (some stuff that seems tame), but yet more risque posts stay up. There seems to be a lack of consistency. And the Social Media giants are simply TOO BIG, and have mostly automated the post moderation process. Then you have large companies like YouTube that go and change their algorithm and remove alternative medicines, as an example, because big pharma wants more dollars. Facebook is flooded by annoying advertising. So much so, that I've mostly stopped using Facebook entirely.
People are coming back to forums because they are more tightly-knit, and the forums that are based on community versus advertising revenue, I think will see the most growth soon as more people get tired of the constant barrage of censorship and advertising that gets in the way of their content consumption.
I know this is one of the main points I highlight to other people whenever I have a chance to have this conversation, because I know that I'm really sick and tired of running into censorship in the "land of the free". And I'm so tired of all the darn ads! Of course, not to mention the highly organized fashion forums tend to have over just a timeline of posts/content via social media giants.