Are you sure they aren’t building a profile? What gives you that confidence?
If you had access to this data, why wouldn’t you try to build a profile?
“COMPLETELY ANONYMOUS” is often not as anonymous as people would expect. This could be a long list of my likes, dislikes, my connections with other “anonymous” profiles, ability to track my nameless self around a city. The only thing lacking here is a name and address.
That may be technically anonymous but I still don’t like it.