What hobbies are still powered by forums, old maps and word of mouth?

I’ve been thinking about how many enthusiast communities still have incredible knowledge trapped in old forums, Facebook groups, PDFs, historical maps and people’s heads.

Relic hunting and rockhounding are two obvious examples. ..Im a bottle guy! The information exists, but actually figuring out where to go, what’s there, and whether you’re allowed to collect can take hours.

What other hobbies or communities are still like this?

I’m especially curious about ones where the underlying information is valuable but horribly fragmented.