This claim is the reason so many developers work their asses off to make something, only to realize that no one wants to buy it. You do customer development before you build the product, not after. Step 1: find need, step 2: find out if people will pay $ for it, step 3: make it.

"Real" business people are very good at steps 1 & 2. It's not fair to call them "idea people" if they have useful executional skills to make those things happen.