You are never so alone as when you are ill on stage. The most nightmarish feeling in the world is suddenly to feel like throwing up in front of four thousand people.
The group started getting bigger and bigger, so Al started replacing Brian on the road, and then finally there was a big flare-up with Dave Marks and he left the group.
I think many people are terribly afraid of being demoted by the Darwinian scheme from the role of authors and creators in their own right into being just places where things happen in the universe.