And semantically, logically, you are 100% correct. But there are other, subjective, emotional, layers to language. Billionaire, business magnate, and oligarch can mean the exact same thing, but they have very different emotional meanings and associated contexts.

I think the author may have a point that by spreading the “HTML is not a programming language” meme, we may be contributing to its lower subjective status.

But this thesis is, by its very nature, subjective, of course.