I think it is too complicated to say 'because of' or 'despite' when talking about how musicians' excesses affect their work. It is in there- the adversity the, euphoria, the darkness, the wildness, the moodiness....all of it. The music and the performances would have been different without the lifestyle. Different, how? We couldn't know with certainty...but different by necessity.
I am a musician too. Personally, I am much, much better in every way when sober - creatively, in playing technique and accuracy (guitar, mandolin mainly). When performing live, I am a bit more nervous when playing totally sober - but not for long - a song or two.
Like Dee, I find I connect very well with players who have some history in this area but have come through to the other side and found calmer waters. What is more they stand a decent chance of going on to create and perform into their sixties, seventies and beyond which is something that too often eludes the musician who continues too long in the wild stuff.
I am still trying to leave all that stuff behind for good and still stumbling. But, the last year has had more sober time and fewer binges than any any other time in my adult life. It has made the distinction between the wonder and adventure of sobriety and the gloomy recycling of lousy drunken experience very stark to me now. I am only on day 9 of this stint but, in planning my future sobriety, music is playing a big part. Not least, I wonder how good I could be. I don't mean in terms of fame and fortune but in satisfying myself as a songwriter and player. Only one way to find out - and it has to be sober.