Ed,
I'll offer my perspective.
Long term success in sales is based on the ability of a person to establish a relationship with a customer and partner's with them to offer solutions to their material handling needs. The hard part is finding or getting into see the key person(s) that actually makes the decision and earns the opportunity to develop a relationship. Often customers are reluctant to change if there are no real issues with their current provider. But you have to be like the Indians circling the wagon trains and looking for your opportunity to get inside. Since customers all have various hot buttons when it comes to capital acquisitions these need to be uncovered and addressed by the sales person. These hot buttons are as many as there are decision-makers, in my opinion. Certainly, no one person can be totally capable of possessing the technical, advertising sales skills you refer to but they do need to be able to draw on their organization to support them with the level of expertise needed by the customer.

A good sales persons need to be like a prospector just keep panning for the little nuggets of gold and recognize the opportunity when it comes along.

I once knew a National Account salesman very successful, great people person but technically incompetent - when a customer would ask him how something worked his reply was "It works just fine." If the customer pressed for a more definitive response he called out his Calvary for support.