Adblock detectors that function in the same vein as "FuckAdblock" look at if the client blocked a Facebook pixel.
Or are the websites providing identifying information like email? (I've never heard of this but I'm not well-versed here).
But who, exactly, is the individual? Well, that comes later. Maybe your blocker fails to block something that is gathering that data plus your identity. Now, all of that activity (that was previously not tied to an individual) can now be safely linked to you, the individual.
Also, thanks for sharing that EFF link, I really like the breakdown of how much entropy they can get from each fingerprint dimension.