Was a lot of it classic word of mouth, email, etc.?
I imagine something like that, but I’m wondering as I feel like there may be some useful pieces of knowledge that may be worth recalling as people gradually start to move back out of the more centralized sites/services.
Blogrolls and webrings
That’s my answer - if you stumbled across one site.you liked, them there’d often be what amounted to a curated list of similar sites. It was more cooperative back then, not about trying to grab and hold eyeballs so you could monetise them.
I now realise I’ve been doing something similar through community’s sidebars because the Fediverse isn’t a competition, if people are doing something interesting in another place then throw in a link.