Hiding subscriber counts is intentional at join-Lemmy.org. They were being displayed about 2 weeks ago, but new users saw them, viewed actively as a form of social proof, and only signed up with large instances.
Problem is, those large instances are starting to break now. They can’t scale fast enough to meet demand.
Moreover, if you signup for a small instance, you can still subscribe to communities from another instance. Communities are shared between instances.
IMHO, we should be displaying stats like response time and integration with the federation network. That’s what is actually important for most folks. If you only focus on local activity, you’re going to have a bad time.