It doesn't apply to HTML because HTML is fundamentally not code that runs, but rather a markup. It's just like how licensing a book under the GPL would be weird and unnatural, because it represents someone's words. JS is code that runs on your computer, just like any other program
There is definitely a grey area, but HTML is pretty far away from it. HTML doesn't "execute" and is very far from Turing completeness. You cannot write programs in it, and that is the key. Pure HTML is very much on the side of "rendering text" and not "running software." Once we start talking about things like LaTex though, the line gets a lot harder to see. Note that whether HTML is "code" is irrelevant. The point is that whether it's "code" or not, it is never a program.
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