Google has a long history of misdirection and slight of hand so this should be looked at through their history.

Would Google do something that causes them to make a lot less money? Likely not.

I wonder if Google is treating our computers as edge nodes running their software (i.e. chrome, js workers, etc). Because it's tracking us on our computers they don't consider it Google tracking us. Then they phone home with calculated cohorts and cohorts are always changing. It's still tracking us but in a different way.