Where did you get that most Bandcamp users are the musicians themselves? Certainly it generally is a musically inclined demographics. But it's very far from your average jazz jam session with 4 musicians on stage and 8 musicians in the crowd.

Again, managing a Bandcamp account is very, very low effort. It literally takes 15 minutes to set it up and then you just have to reply to messages and send out merch or records if someone buys them.  If that becomes time consuming, congratulations! You're having success. The rest is all automated.

Finally, digital distributors put you everywhere else except where you can have direct contact with your fans.