Every Lisp I know of has SXML either baked in, or as a library because it absolutely can represent the fullness of HTML...

    (parrot (@ (type "African Grey")) (name "Alfie"))

    <parrot type="African Grey"><name>Alfie</name></parrot>

Yes, (HT|X)ML have a semantic model that that can be represented in Lisp syntax, but so does everything else (well, every programming and data representation language, at least.) They don't do it with the same (or simple parallel) single simple syntactic fiundaton as Lisp, but with something more complex.