Tons of people die every year from alcohol poisoning. And of course from passing out drunk and choking on their own vomit.
Shit happens.
If she really had stopped partying completely and got "clean"...something else would have happened.
Remember when Stevie Ray Vaughn kicked alcohol? He was finally sober for the first time in his adult life and did a bunch of interviews talking about how happy he was and how much better he was playing his guitar and how healthy he was...and then had a helicopter crash and died a couple of months later.
Life is funny like that.