It's often a very big leap for an individual to open up a project to more contributors and a community. They have to change how they do things, how they spend their time, negotiate the best way to do things, etc. Not everyone wants to do that (or has time & energy to). But as you said, it's amazing when projects turn into something bigger and/or better. We need a good mix. Nostr is probably too much on the lone wolf side at the moment (including me with Nosta).