Yeah #[6] was the original creator of nostr and was building on bitcoin & lightning network beforehand, same with #[7] and many other devs you see building nostr. Here’s a short article that kind of explains it https://fortune.com/crypto/2023/02/21/bitcoiners-flocking-to-nostr-social-network-jack-dorsey-edward-snowden/amp/
And as fiatjaf says in the article, the bitcoin integration is more of an add on feature than an integral part of the protocol.
I joined in December and can tell you that the conversation topics are becoming more diverse week by week as more and more people join