In my previous airline the flight deck was not allowed to interfere in case of a disruptive pax. Especially on problematic flights we had many drunk and aggressive pax and often it was young girls in the cabin. How in the world can they prevent anything? The airline wants them to sell alcohol. None of the problematic pax respects the cabin crew. In fact some of them don't even respect the authority of any pilot. That's one of the biggest downsides of those cheap prices. Flying is like taking the metro nowadays and that's what you'll get.
Personally I'd ban alcohol on the flights or a maximum of one alcoholic drink (excluded the hard stuff) and any drunk passenger should be denied at the boarding gate latest. Someone that is drunk is a risk factor in any accident.