i think most media types seem to want 1) tools that make it easier to use as a broadcast medium 2) some monetization/revenue stream or way to funnel followers to products. Joining is about network effect FOMO and low barrier to entry. If the level of effort is too high relative to perceived value attained, then it falls off.

Nostr is at this weird place where theres a few thousand regular users, but no compelling reason for most other users to actually use it when alternatives exist and have a stronger foothold. Needs content and features you can ONLY get on Nostr, or with lower friction. 

Speaking from personal experience I stay because its fairly permissionless to build on, but for most people that holds little to no value. I also know that any new thing that appeared on twitter will show up on nostr just as quickly. I refuse to use Facebook, Twitter, Reddit et al as fully captured but recognize this is a minority held viewpoint. In short, the reasons I stay and build is not compelling in the slightest for the average person. To get to that point for the masses we need to build, refine, and educate more.