Just like with the presumption of innocence and the demand that the state prove the guilt of a defendant "beyond a reasonable doubt," the greater good is nevertheless served by applying the principle, even if it means that in a few cases, a guilty man may walk free.
I understand the principle just fine. Others don’t understand that it is a two-edged sword. And given the likelihood that jurors are selected for their “stupidity,” I would argue that negative outcomes are more prevalent.