Consider the following sentence:
he moped around the house, upset because he had crashed his moped
See the problem? The words "moped" are one example of the kinds of words we usually refer to with colorful language only repeatable after the watershed. They are homographs - words which are spelled the same but pronounced differently. There is a subset of homographs which are not just pronounced differently, but actually have a different number of syllables depending on which meaning you are going for.
Along with file and file, learned and learned, tier and tier and a few dozen others, these represent just one problem with counting syllables with a computer.