To take an extreme example:
Selling a starving person a meal doesn't just extract the price value, but creates it too.
You might argue that there are better or more efficient was of creating that value, but the fact that it is created is inescapable.
If you want to make a utilitarian value argument against it, you need to compare it to a real world alternative subject to scrutiny that is just as harsh, not a perfect world one.
Good salespeople are trying to connect customers with solutions that provide them value that they otherwise wouldn't have access to (generally because they weren't aware of it). Obviously, in practice, the line between that and the more negative experiences can be fuzzy and vary by one's perspective, but unless you have someone in-house who's dedicated to searching for new solutions... And then, they turn into a sort of salesperson themselves, with ambiguous allegiances. At least someone from the outside is someone you will always be skeptical about.
Engineers can create things that don't have value and salespeople can create value by matching problems with solutions, there are a lot of things we all very happily pay for after all. It's just not that simple.
What a bad, reductive point of view. While it's true there are shitty bad salespeople (as there are engineers), try selling anything without doing any selling of the product. Once the company gets to a certain size, having someone work on sales full time instead of getting an engineer who doesn't whan to do that work, work on that part time.
To take an extreme example: Selling a starving person a meal doesn't just extract the price value, but creates it too.
You might argue that there are better or more efficient was of creating that value, but the fact that it is created is inescapable.
If you want to make a utilitarian value argument against it, you need to compare it to a real world alternative subject to scrutiny that is just as harsh, not a perfect world one.