Long term, your customer still doesn't give a shit that your product is built on a bleeding edge javascript framework (except if it has more bugs as a result). And salespeople are perfectly capable of grasping "if we don't fix this technical debt, it'll be really difficult to do anything very much with the product in future". They're just immune to "look, open source, new architecture, shiny!"

The salesperson is the one that says "you're not going replace horses with automobiles, unless they're faster or more reliable than a horse".

As well as the one that says "don't make a faster aeroplane, make one with lower fuel burn instead"

Building on a bleeding-edge JS framework for the sake of bleeding-edge is poor practise. If there is some advantage to using that framework, though, the customer may well care. What development monkeys, attracted to whatever shiny thing comes along, are you describing?

You're not gonna get much enthusiasm here for negative dev stereotypes, especially if you're gonna cast sales as noble protectors of the business in contrast. Many devs (especially in "enterprise") are quite conservative. In fact, I've seen sales/management sometimes care more about the latest buzzword shiny than development.

> salespeople are perfectly capable of grasping

Doesn't mean they'll care, especially if they'll be out, commission in hand, by the time the debt hits.

> The salesperson is the one that says "you're not going replace horses with automobiles, unless they're faster or more reliable than a horse".

I'm not sure cars were either of these.

And the point is, how do sales know what the customer wants, if the customer doesn't know what they want?

> I'll add - sales would suggest building a faster horse.

Wrong - the customer would ask for a faster horse. A bad salesman would sell them one. A good salesman will get them to want a car.