Can confirm to some degree as I built this system almost 10 years ago. Back then it was used for rich data in 3 apps that were all turned down years ago. I've been out of Google for a long time, so I don't know if it's still around or what it would be used for anymore.

I believe this is why Amazon order confirmation emails nowadays don’t state what you purchased!

And facebook also tracks what you browse. (And Amazon lets people die in a storm.)