Earlier quoted context omitted.
> This is a terrible idea - the data isn’t yours until it’s been explicitly given. I couldn't disagree more. I think the owner of a website should be able to track whatever information they please about your session.
Would you also support Wallmart following you around their store, keeping track of which isles you walked, which way you looked, conversations you had with your spouse next to you as you shopped, etc? It's their store. They should be entitled to own everything about you when you walk into their store, right?
When I worked for UK financial company we would track how far people were going through our form wizard to see where the paint points were. The personal information never left the web page, but it would report back telemetry telling us how many people dropped out at each stage. That helped us to do split testing, e.g. does this label make more people fill out the form, etc.