Why isn't shapeshift.io listed on coinmarketcap?

People can exchange altcoins on shapeshift.io. That makes them an exchange. Why isn’t shapeshift.io listed on coinmarketcap then? They should be listed there and contribute to the price charts. If I was to make a shapeshift.io rival web service and provided a price index API for sites such as coinmarketcap, would they accept it and start tracking the price of nubits according to my hypothetical service?

I believe ShapeShift uses outside exchanges like BTER and acts as an intermediary. Adding them to CMC would cause duplication of numbers.

B&C and shapeshift, cooperation?

Yes and no. What if shapeshift.io utilizes bitstamp to reduce the risk of bitcoins losing their value? But wait a second, bitstamp does not have NBT trading pair at all. That means there is no duplication possible! In these cases, coinmarketcap should include data from shapeshift.io.