I agree that the customer is the ultimate measure and I'm a fan of this whole lean startup thing. You're right that the only thing that ENDS UP mattering is what customers think. But to use that as an argument against having a co-founder seems strange.
Co-founders disagreeing doesn't result in a flip of the coin to see whose opinion they go with. There's a heartfelt and intelligent discussion. Logic, experience, and a bit of intuition. One co-founder might say, "I know the team over at CompanyX who struggled with the same thing. They chose Y-- let's see how it worked out for them".
If the OP had a co-founder who was smart about marketing, design, and conversion funnels-- there'd be very few arguments in those areas, but there'd sure as heck be better decisions made being there.
In short, I agree with your point but I don't think it applies to this discussion.
Co-founders disagreeing doesn't result in a flip of the coin to see whose opinion they go with. There's a heartfelt and intelligent discussion. Logic, experience, and a bit of intuition. One co-founder might say, "I know the team over at CompanyX who struggled with the same thing. They chose Y-- let's see how it worked out for them".
If the OP had a co-founder who was smart about marketing, design, and conversion funnels-- there'd be very few arguments in those areas, but there'd sure as heck be better decisions made being there.
In short, I agree with your point but I don't think it applies to this discussion.