Earlier quoted context omitted.
Sure, until that information is used to give individualized prices and other things. Or used to hide things or show you only things the algorithms decide you like....or should have according to them. Already i've read things about hotel websites and stuff altering prices based on which device you're using to browse their site. In a world where your personal shopping information is bought and sold and things become in…
It's much easier to do that for hotels than for groceries since comparison is harder. It will be quite widely known and sightly abused if your grocery chain starts doing that. The shops will always have the reference price in public after all. The pricing difference that actually matters (moving old stock) is already mostly done without personalised data. Sales are a standard.
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.