If we're including promotions or membership discounts, then coupons fit this definition of price discrimination. And those have existed since the 90s at least.

The problems show up when different people don't have access to the same coupons published by the store. Most coupons are fine.

They haven't had the ability to do the significantly bad kinds of targeting until recently. This is a new problem even if it's similar to old practices at the surface level.