Well, there is some method to that madness.

Sure, you could take multiple trips through security in order to accumulate liquids on the sterile side. But the more trips you make, the more times you submit yourself to TSA screening, which increases (slightly) the probability that someone will discover that you're up to no good. The efforts you would need to go through in order to avoid detection on multiple trips provide more opportunities for you to screw-up and reveal your true intentions.

As to how much the chance of detection actually increases in this scenario, and whether that increase is worth the overall hassle and expense of enforcing the 100-1-1 rule, I'll leave that to others far wiser than I to decide. But a minimal increase in detection is still an increase.