I think I see the Pubky app itself as a first iteration of the idea. Like Damus was to Primal (perhaps that's a bad example)? Someone else could build a better version of it on top of the concept right?

It's the DHT implementation that I think is the important part. And there appear to be many different use cases for it. It's just that - like you said - there's no traction and no one seems to be using/building on it.