For now, with brick and mortor businesses because it's hard to do that in a physical place. With people increasingly ordering things online it becomes easier and more profitable to do that.

If someone has your spending history, sees you buy something frequently, they have no incentive to put it on sale. Likewise, if they see something you've maybe looked at but not bought, they can put it in sale and tempt you.

This is just one example. I'm sure marketers can come up with all sorts.