Oh, and to answer
“How many of these would you have to change to make your browser look different?”
Just one of them would be enough (using this definition of “unique”). All of them have to be the same for two browsers to be considered identical. That’s why it’s so easy to have a unique one.
I can change my fingerprint just by dragging the window to the other monitor, since my monitors have different resolutions, and screen resolution is part of the fingerprint.
But I highly doubt any outfit who is actually using this technique as a cookie replacement is going for exact matches. They've probably defined some sort of similarity function, and they consider anybody who scores above some threshold to be the same person. That's plenty good enough for their purpose, which is to sharpen up ad delivery and deliver improved audience analytics to their clients. A few false positives or false negatives wouldn't matter.