i think it has something to do with the fact that there would be the same number of base molecules and acid molecules in an aqueous solution. it would be like in a pan balance, once you add too much to one side it will be uneven, and it usually takes a great deal of accuracy to get it centered right. the same would happen with an acid-base titration, when you try to get to a pH of 7 you are trying to have the same number of basic molecules to the same number of acidic molecules.
i think that i am right, though not 100% certain i also had some confusion some time ago around this matter.