Hello. I'm someone who's previously/currently had accounts with 2 other nonprofit Unix shell account providers similar to SDF since approximately 1996/1997, and first found out about SDF maybe 10 years later while looking for other email-account-provider options. Then, last year, I saw SDF's Mastodon instance listed on joinmastodon.org, and decided to sign up for an account there... which eventually (thanks to the email announcement that was sent to users registered there) led me to this Lemmy instance.
I suppose the main reason why I decided to sign up here is out of hope that ActivityPub/Fediverse will become similar to, but better than, the various types of discussion forum systems (Usenet/NNTP, mailing lists, mailing list archivers like Pipermail & MHonArc, phpBB/vBulletin-style web forums) that were popular in the '90s and '00s. Personal blogging/microblogging systems (Mastodon, etc.) aren't an adequate replacement for newsgroups/forums, as far as I'm concerned; to paraphrase something I read elsewhere, too much of so-called social media is mostly about "look at me", as opposed to "look at this" (i.e. organized by topic).
(By the way: Lemmy currently seems to have some sort of incompatibility problem with QtWebEngine and/or the Falkon web browser. I initially tried to post this from Falkon, but the "Preview" and "Post" buttons were disabled even after typing some text, so I ended up posting this from Firefox instead.)