Speaking as someone with a food addiction, I can honestly say that in my belief it's the person with the addiction who has to take responsibility for their actions. Feeling sorry for someone is all very well, but noone else (however well-meaning their intentions) can sort an alcoholic's life out for them. (That's not to say that having a strong support network won't help btw). It's all too easy these days to blame external influences for your emotional problems ("oh, my boss was horrible to me today, I had to eat a whole packet of biscuits when I got home" etc). I don't believe the outside world is any more cruel today than it ever has been. Or that human nature has changed a whole lot.
I agree that if you're not fit to perform (interact with an audience) then you probably shouldn't be on stage. Anyone who has paid to see a performer has the right to expect a PERFORMANCE by definition.
I have no idea who Davy Graham is and I've never heard his music or seen him live, so I promise I'm not having a dig at him lol...