Source? The first rule of adtech is to not trust your publishers to not defraud you.
This is also why companies like Tealium and Segment are now worth billions of dollars. They provide a single integration point that funnels events to dozens of marketing companies' server-side APIs.
Sounds like they make the blocklist-curators' job easier.
If "the sites you visit" are the ones talking to Tealiums and Segments, it is trivial for "the sites you visit" to lie about the browser IP address and make it look like requests are coming from all over the world instead of just one box sitting under $FRAUDSTER's desk running a script.
The first rule of running a megacorp is... oh, wait.