I think it is not a good idea to make a generality of it, people look at arts in a different way. I don't think suffering is always "caused" by arts or the mastering of an art, a lot of people are already tortured and use arts as an outlet to their suffering.
I agree. Art is so subjective anyway. A lot of what's considered great or genius isn't always a direct result of hard work/suffering, talent or even skill. Like Duchamp's urinal which is in all the art history textbooks and is considered revolutionary, that definitely was not a result of suffering or hard work. Also, if you look back at all the old masters, they were all male. There were plenty of female artists of equal talent who probably suffered or worked as hard and will never be recognized as great. So no, I don't think in art, suffering = success or greatness.
But there are certain things that will need work and persistence. Like if I wanted to operate on people, then yeah I need to put in some work to learn how to do that. If I wanted to be a body builder, sitting around probably won't help. But I don't really think that has to include suffering also. Maybe some challenging situations, but not suffering. If you were suffering, then I've got to wonder if that's something you should be pursuing or question how you're handling things.
Life doesn't have to be that way unless you want it to.