One could also get a large amount of liquid or other substance on a plane by simply finding a stash point and having a few dozen people carry the allowed amount through security and deposit it in the arranged location or hand it off to somebody. It's not as if someone planning an attack wouldn't have the resources to do this.
This makes me laugh. You can do a lot of damage with 100 ml of certain clear liquids, and some of those liquids are quite easily produced using things available around the house. I obviously do not condone this, however my point is that this whole "restricted volume of any fluid" bollocks is merely a facade.