I miss forums too, and I blame the "mobile revolution" for their demise.

Forums are ideal for long-form discussion in text-format. But they don't really work well on mobile devices where typing is cumbersome and reading a lot of text to catch up on a thread isn't all that enjoyable.

And you remember when forums were trying to be mobile friendly by introducing things like infinite scroll? It just didn't work. Meanwhile "the masses" were flocking to sites like Twitter where content was delivered in short bites and they could doom scroll until they got bored.

Forums still exist they are just niche now and it's harder to attract a user-base when so many people prefer to use social media for their "discussions" because that is better suited to small talk on a smart phone.