I'm not a security expert so I may be wrong (if so, someone please educate me). My impression is that if you own several websites and trackers, you can identify users by the specific combination of blocked and non-blocked trackers, plus data about their machine/OS, ISP, screen resolution, and browser languages, as well as checking to see if browser permissions are turned on for notifications, location, and the like. I'm not sure you can prevent that with a javascript-based approach alone.