Product development is dictated by marketing strategy.

How would you build your product if you don't know what the market conditions are? How do you find out what the market conditions are? By segmenting the market by behaviour/need/price sensitivity, then targeting a segment which is underserved (or you can serve better), and finally positioning your product to cater to that particular segment with specific product design, messages and distribution channels.

Marketing doesn't develop the product. It just designs it (writes the specs).