Sorry, Dick, but I read the title and what I saw the potential for this becoming yet another thread that develops into long wrangling from the same group of people taking up the same positions without there being any hope of resolution. If it doesn't then I will apologise to you. I sincerely hope it doesn't because to many folk enthusiasts that I talk to Mudcat has become something of a laughing stock because of this.
So I will give my contribution and the retire and watch what happens.

For many busy profesional performers in all branches of the performing arts, there comes a time when handling their own appearances/engagements/contracts/publicity etc. takes too much of their time and they are pleased to hand over that business to an agent for a percentage of their earnings. I would reckon that it is a pretty tough job without a guaranteed income. Relationship between an artists can have many points at which it can become fraught.
In 50+ years of running folk clubs and festivals, I have worked with very many agents. They have ranged from the the excellent and utterly reliable to the hopeless and inefficient with most somewhere between the two extremes. Just like all the other people that I interact with in my life, in fact.