I always thought the rule was about damage (liquid spilling onto your bag and other passengers' bags) rather than safety? That's based on how the rule was shaped: 100ml containers with no limits as long as in a sealed plastic bag.

I wonder if they'll walk this back? If you put a 2L water bottle in the overhead compartment and hit enough turbulence, it could open and drench the entire compartment and other people's luggage.