Bacteria

At the risk of committing heresy, I wonder if instant or dry active yeast could be the basis of a good sourdough starter. Here's my reasoning:

I'm told that dry active yeast has been 'engineered' to be very active and supplies a very high concentration of yeast to make bread rise quickly and consistantly. Intant yeast is very easy to use but works so quickly that it sacrifices the depth of flavor one gets with a long, slow ferment.