Fathom "Doesn't use cookies" - so how does it have any concept of things like sessions and unique users then? I really want to know. The website doesn't explain

Fathom "Doesn't use cookies" - so how does it have any concept of things like sessions and unique users then? I really want to know. The website doesn't explain this, it just drops that line and walks away. This is like saying a car "doesn't need tires" - sounds interesting, but wtf does that mean? I'm assuming it isn't using local or session storage either, because it's pretty disingenuous to replace cookies with a newer technology with about the same purpose and then pretend it's somehow more 'privacy respecting.' I imagine if its JS rewrote every link on the page to persist some random id as a URL param, it could theoretically accomplish those basic analytics tasks - though it would get tricky when navigation happened by forms or via JS. Another theory is that maybe they just use IP as a proxy for a user. Pretty flawed since office buildings or home networks with multiple users will just appear as one "person" with a nonsensical usage pattern. (of course, my above "idea" is functionally identical to a cookie, but the idiot politicians don't understand any of this technology, so it would probably be considered "ok" by the law even though "cookies" are somehow evil and scary).