This alcohol-induced sleep sickness results from drinking too much, too often, such that your body is regularly deprived of rest and un-poisoned REM. If you don't make time to recover, your body will take time from you. Especially if you can drink instead of eat--without barfing.
Passing out is generally less likely to get you in trouble than blacking out for long spells. But it's lonely. One night, I was carted around to three different parties, and simply curled up on three different couches. "I met you, but you were asleep." Fuck is that supposed to mean?
Once your partying approaches Barrymore status, prepare to forfeit household items. I once held a glass of Chianti upright all night, only to be startled awake, thus spazzing it onto the sheets. That's if you make it home. There's nothing like fleeing a strange house in mussed clothes and crumbling mascara.
Besides making you a literal drag, habitual pass-outs cause occasional snares in relationships. You miss everything that happens among those friends with enough carbs and stamina to stay conscious for more than two hours and, generous as your intentions may be, granting blanket permission for your special guy to screw you in your sleep is not always the best demonstration of affection.
Passing out's not the most terrible thing you can do. However, it's exhausting, makes your skin shitty, your friends fretful, and your dry-clean-only clothes smell. It's often preceded by a period of blackout time, much like being clubbed in the head. Just long enough to get a bad reputation and flirt with strangers. It gets old after a while, though. Why not pencil in a nap, a sandwich, and a few extra moments of lucidity?