Take terrorist Ramzi Yousef. Not content with simply bombing the Twin Towers in 1993, he moved on to airplanes. In 1994, plans to hide liquid explosives in contact lens solution bottles were discovered on his laptop. Yousef’s goal? To destroy 11 jumbo jets simultaneously in midair.
When I was with the Transportation Security Administration, I saw a mock-up of this evil-genius bomb. Trust me, you would gladly surrender your liquids at the checkpoint if you saw it. And you would want everyone else to do so as well.
Then why did the US wait until 2006 (12 years later) to limit liquids if Yousef had such an "evil-genius bomb"? And don't forget, that the most accepted theory is the nitroglycerin was infused in stabilizers that looked like cotton wool balls, so it didn't even look like a liquid.