I think we'd be silly to not recognise that there are some tradeoffs between privacy and UX. Facebook tracks your cursor for a reason, they're analysing what users do and changing the UX based on it. I can imagine wanting to look at this data using any number of filters for a/s/l/etc., and once you're cataloging enough criteria tying a session to a specific user can be done as an afterthought. I think GP is correct about most users valuing UX over privacy, unfortunately.