I never understood the restrictions on liquids and I'm convinced it's to ensure you continue to buy overpriced soft drinks/water in the departures lounge; along with having to trick unsuspecting folks into paying up to £2 for a ziplock bag.
Hypothetically if an odious individual wanted a large quantity of suspect liquid post security they'd simply have 20 folks on cheap tickets go through security with 100ml and mix it together in the toilets in an empty container?
It's absolute theater.