@fedilore i get that, but thats too much work for a single website to try to track their visitors down, more likely stuff like this happens:

these 10,000 IP visits certain 10 website regularly through our network
vs
these 10,000 IP visits certain 10 website regularly through our network and come from those other 5 websites outside our network

what is more likely happening?
- single websites trying to figure out who a very specific visitor of them might be
- whole networks trying tracking and building user profiles based on hard facts like time, ip, referer, user-agent or even browser fingerprinting