There's definitely some nostalgia involved, but I feel some things from the previous Internet have been lost. Discord communities are at least a reasonable approximation of the old IRC channels, and there are other modern analogs to "old Internet" things, but the forum format is something that I feel has died, and I miss that a lot.
Perhaps the main difference between forums and modern sites like Reddit, or Facebook groups, is that forums were a natural fit for slower, longer in-depth conversations. It's normal to have a forum conversation that lasts days, if not weeks, and where the posts all consist of many paragraphs. A site like Reddit is designed for older posts to sink. Same with anything that employs a "news feed" page format. Yes, forums are still around, but they're a shadow of their former selves, and often seem to have an old userbase.
Reddit has slowly died though as it has become a much more popular site. The people I used to enjoy interacting with have slowly gravitated away, while the quality of the average comment has significantly degraded. HN isn't a great replacement either, but outside of a handful of small subreddits I have found myself frequenting it more.
I'm a member of at least half a dozen phpBB forums right now. They do still exist. Even if Reddit is more popular, remember that forums in 1998 didn't have millions of members either.
Perhaps the main difference between forums and modern sites like Reddit, or Facebook groups, is that forums were a natural fit for slower, longer in-depth conversations. It's normal to have a forum conversation that lasts days, if not weeks, and where the posts all consist of many paragraphs. A site like Reddit is designed for older posts to sink. Same with anything that employs a "news feed" page format. Yes, forums are still around, but they're a shadow of their former selves, and often seem to have an old userbase.