I disagree; I've been involved in products whose sales involve the sizes of TCAMs on a Cat6K and the particulars of BGP regex filters, and while it was vital to have someone who could address those questions involved in the sale, and while the decision on the sale was being made by people who know what those things mean, it was pure sales execution that turned the engagement from a science project to a "nice to have" to a "must have" to a purchase order.

I don't think we're necessarily disagreeing. I'm not saying technical details are going to make a sale (almost ever), but if one of the members of the sales team (note that I'm classifying the "sales engineer" as a salesman) can grant credibility & real world experience to the lofty promises that the typical salesman makes, it adds a level of differentiation that can—in some instances—make or break a sale.

Also, to clarify, it also really depends on the nature of the industry, the product, and even what we're considering technical details.

You seem to be getting close to saying that the product actually being sold hardly matters, which I find hyperbolic.

This is the kind of thing that used to be said about Microsoft, that they were good at selling in spite of having bad products. But the truth was that Microsoft knew very well what their customers needed and wanted, and for the most part did a better job building something that met those wants and needs than their competitors.

A very simple sales model is that your prospect has to understand what your offering does, believe that you can deliver, and then find a reason to act. Technical expertise and experience can contribute significantly to the first two steps (although the ability to clarify benefits is critical) but "sales" is normally more important for understanding how to get a prospect to act/purchase.