This does remind me of some of the crap that I was turned off by when I was a web developer. Heat maps, pointer tracking, etc. You can learn a lot about a person from their keyboard and mouse usage.
Discussion
Yeah it tracks everything - mouse movements; how long you pause over what, clicks; related searches and millions of other data points to create profiles and then compares you to other profiles and predicts what you might want to look for
If it makes you feel better, blocking JS scripts hinders a lot of the creepy tools websites use. Some websites just break though. Or browse in a separate container/browser that doesn't have login data stored and then copy and paste the item link into the credentialed browser or container when you want to checkout. I wonder if they have a guest checkout option.