Did you actually bother watch the doc ? I found it genuinely moving and sad. Her addiction and her problems in dealing with it, were a product of her fame and the pressure it placed upon her at such an early age, they didn't go hand in hand. Indeed she came across as much stronger and happier before she broke it really big in her career, and went from starlet to worldwide superstar.
It's a different scenario to an addict who is just an ordinary joe but they're both crap situtations and you'd have to be a bit of an arse not have some sympathy with either case.
That Britney Southpark episode already nailed this to some extent, a story as old as the concept of celebrity. Amy just shows us how a fragile young person can understandably go off the rails, with so much thrust upon them in terms of commercial and media pressures, not to mention family and supposed friends hopping on the gravy train as well, throw in some Daddy issues and it's a lot to deal with while still basically a kid.
Without enough good people around, with her best interests at heart, you see her almost fed to the wolves, be they people close to her who she loved and couldn't see their true intentions, promoters with dolla signs flashing or the standard paparazzo vultures, hounding her every movement from flat door to rehab centre gate, they all get their pound of flesh.
It's easy for people to say, but yeah you're loaded and everybody loves you, stop whining about your troubles love, don't succumb to the crutch of addiction even with every vice you can think of available on tap etc. Without walking a day in their shoes though, how do you know if you'd be strong enough to handle everything thrown at you and stay balanced through it all ?