The problem is that candidate is undistinguishable from a chameleon who will be pushed around either by popular sentiment, special interests, eventually adopt p

The problem is that candidate is undistinguishable from a chameleon who will be pushed around either by popular sentiment, special interests, eventually adopt policies you disagree with etc. Taking some kind of concrete stand at least lays a base of where they're coming from and provides metrics of success or failure once in office. The blank slate is more high risk high reward I guess.