Actually the airlines do not have the power to 'collectively' do this. Any decision to ban someone can only be for their own services.
Being banned for flying 'forever' seems a little extreme. A life sentence for murder in the UK generally means 20 years or so. Do such penalties actually work as a deterrent?
And, IMHO, airlines should look at their {expletive deleted} pricing policies for on-board drinks. It is no wonder the punters seek to pre-load when they can buy a pint at the airport (at already obscene prices) for less that a 33ml tin of crap lager on the plane. They can control on-board sales a lot easier than those purchased airside.
And on flights ex the EU (for example to Switzerland) it's close to 90% profit as they sell duty/excise/VAT free drinks at the same prices as they sell it on intra-EU flights.