It's a mistaken belief. Inexperienced sales people might be forgiven for thinking that doing the customer a favour is a good way to proceed because the seller will then buy lots more product at list price as a result. Those of us with more than a few years experience will know that it almost never happens. For the seller, in effect, to buy the business with a crazy offer is not a good strategy. Let's not beat about the bush.
All commercial enterprises are in business to make money.
Unless you make money, you die. It's a fact. I offer a tremendous deal now at some point in the future, the buyer can reciprocate with a nice big order for something else. It seems to the buyer that the selling organisation offers tremendous value for money. But it a situation that cannot be maintained indefinitely .