I certainly agree - drunkenness on planes is undisputedly the single leading cause of incidents, and in the past few years I have witnessed far too many of them, but in a way, sadly, it doesn't have to be either/or. Although this is just a hunch, I'm guessing that particularly in the 'front' of the plane, crew don't dare to refuse serving alcohol to people who are clearly already intoxicated, and in fact more generally, some airlines are far more pro-active about avoid alcohol-fuelled air rage incidents than others. However I think it is a more straightforward case as long as airlines are held responsible the way any bar tender would be held responsible and in trouble if they served alcohol to people who then hit another customer in their bar. The other thing is that in my experience, air rage is not really an either/or thing. Most of the cases I have witnessed exploded when the alcohol problem was then 'ignited' by an additional incident (actual cases I have witnessed in recent months: in one case, cabin crew finally refused to serve more alcohol to the passenger who then gets upset, in the second, drunk passenger precisely became very loud and another passenger asked him - very politely - if he could just bring his voice down as kid was sleeping - that led to insults and intimidation by the drunkard and escalated from there on. In the past i have also had similar cases with always that same scenario that the alcohol either leads to noise or meets a pretext and things degenerate onwards). In other words, while alcohol can lead to bad results, and x other factors can lead to bad results, the combination alcohol + x can lead to even bigger problems.