There's a tension there, because the social graph is the most game-changing element of Nostr. Nostr as the social layer of the whole Internet is a largely untapped potential, and private follows obviously limit some of that potential. If all social graph data is private, then a large chunk of the Nostr value proposition disappears, IMO. However, allowing users some discretion would be good.

Totally agreed, I'm not sure what the right solution is. Private groups highlight this tension because you might want to follow people you're in a group with, but then you're actually potentially leaking data about your association that would otherwise be private. Something to think about.