Some drunken mistakes have consequences. Like if you get drunk, drive, and kill someone. I guess the idea that such people should be held accountable is unacceptable? I mean it's just a drunken mistake. It shouldn't ruin their life, right?
Some "mistakes" are big mistakes. We would rather not have people make those horrible mistakes. So, society has constructed norms, over time, to minimize people making these mistakes - like don't get drunk and drive because the penalties are very high. Also, don't get drunk and fuck around - same reason.
But if you do get drunk, get a designated driver, or take an uber/ taxi, then that's a workable solution too. Likewise, if you insist on fucking around, get birth control or the morning after pill (also a workable solution).