I'd disagree - at the ends of the curve, there are a lot of products that are effectively identical, at which point it's a race to the bottom on price (often meaning a slow decline in features until things are "cost-optimised") unless they can bring another value-add to the table which is where salespeople come in. Some of the best companies with the best products have extensive sales teams because they don't race to the bottom on price - they outcompete on getting first to market of features that they only get to because they understand their customer pain points deeply and find out when the value add is.

I work in the semiconductor industry. A new chip might be designed to run 500+ different protocols, if not more. Coincidentally I had a meeting with one of our senior fellow lead architects the other day, who said a good 60% of those protocols came from suggestions by the sales team. These were requests by customers with super niche requirements you couldn't even imagine, even if you had an army of postgraduate architects who spend all day reading papers (which would be prohibitively expensive). Sure, a chip designer might know to put the latest USB standard on it. They might not know about some obscure broadcast protocol used by only 4 or 5 companies but is the backbone for almost every Premier League football game you watch on TV.

Good products are often only good because the sales team was out there trying their hardest to start a dialogue with a customer to win business, and in doing so listened to them and acted on that.