In just about every business relationship I have with a vendor, there are two people talking to me. A sales guy who doesn't work on the product, and an engineer who does. The sales guy sells me the product, and the engineer gets me to buy it. It's far from standard to have suits get their hands dirty.
My experience is similar but with a key difference.
The sales team often consists of a sales guy who has barely seen the product (as you said) and a "systems engineer" who should not be confused for a developer. The engineers are often technically skilled members of the sales team that are experts at deploying the product and using it in customer environments. That said, they often have development skills (from previous experience) but they are certainly not getting their hands dirty with code in this role.
The "suit" co-founder of a start-up should be playing the role of a systems engineer and the account exec rolled into one because the "technical" co-founder rarely has the right personality/sales experience to be involved in sales.
Obviously, if you do manage to find a technical co-founder who has the systems engineer skills then you can change up the roles a bit but, in my experience, such people are incredibly rare (even in successful start-ups).
