Why do you care? Isn't it better to just focus on perfecting your art, or your code, and not waste time trying to prevent people copying it in some way.

People are going to copy anyway, everything is a copy of something. But if you create your own style so perfected that it cannot be copied without tremendous amount of time, you are already ahead of everybody else in your skill.

Also, more time to develop your skill than to waste time on trying to prevent somebody else doing the same thing.

You could imagine using a special filter to pass your html/css/js though that applied a special transformation that you could later on try to recognize. Perhaps it renames all of the variables with some pattern or from some dictionary that you could later try to use to see if the code matched the pattern. This is along the ideas of stenography.

My guess is even basic obfuscation of his code via minification/compression would eliminate the majority of these copies. The version of his portfolio linked in the article has no obfuscation (granted it could be in dev mode)

No. But you can just diff the code and see it's XX% the exact same code.