Great points on both sides. I think a top in the world business person is as helpful for a company as a top engineer, but this doesn't have to be a co-founder. It can an advisor or later hire that has a transformative effect on a business.

Also I would point out consumer internet business people might not be able to have the same impact as a top bd person for an enterprise software company as ES companies have greater needs on building real sales organizations while consumer internet relies on marketing a social phenomena.