Lindsey addresses the above in this article. Among other things, he says it's much easier to get his work out via Fleetwood Mac than under his own name. Upon the release of
Say You Will:
"I spent about seven years trying to get my material that's on this album placed and heard." "I felt an extreme need to have it have a home and get it out so someone could hear it." "I would be completely happy to continue with this [Fleetwood Mac], never to pursue anything solo again. Because it's a hell of a lot easier":
https://www.fleetwoodmac-uk.com/articles/FMart115.html