I had a studio partner who took this idea as gospel. He was certain that art could only be created as a result of suffering. He ended up "suffering" cognitive dissonance... turning himself into knots to try to justify the fact that he greatly admired Monet, Manet, Gauguin, Miro, Vermeer, Matisse, and many other artists who he could not define as "tragic" or expressive of suffering.
St. Luke, from what you have said of this guy in the past, he also suffered from Parkinson's which begins with cognitive dissonance. That is something people do suffer from, and he may have had other mental issues he suffered with, from the things you've describes of him. In my opinion, he probably shouldn't be shamed or made wrong for the things he was dealing with in his psyche.
As far as needing to suffer to be a "real" artist, I agree that this concept is not true, nor does one need to suffer to be a great artist. I have seen things in some artists' work that have had hard life experiences which seem to reveal itself in the work, but I have also seen the opposite, which tells me that this concept can't possibly be true across the boards.