Your comment shows you do not understand the 'customer development' methodology Eric is talking about. You never stop building. You build concurrent with customer development.
Seriously, read up on it. Don't just dismiss it as paralysis analysis. There's real value here.
I agree that there's a ton of value there - but I've been involved in projects where the "suits" want to do all sorts of bullshit AdWords/Facebook Ad tests, surveys, storytelling, and God knows what.
For fuck's sake, you have a vision. Act on it. Then get some feedback.
Having a vision is important, and it gets the ball rolling. The important part is: Get feedback as you're acting on it. The problem comes when you spend too much time in the cave building, or too much time not building crap, doing a survey. Do both!
Seriously, read up on it. Don't just dismiss it as paralysis analysis. There's real value here.