"It is reasonable to say that HTML markup is code (and writing HTML markup is coding), provided that people understand that it is comparable to using coded notations when talking or writing. Think about the use of product codes, or using special code books when sending telegraphs, so that short coded presentations stand for long statements, or using colors as codes so that red means "stop" or "warning" or "hot". It's a matter of using some notational system which has been specifically agreed upon. (Actually, natural languages are not completely different from codes; they too are based on agreements, just more vague and implicit.)"
To be honest, it's a bit silly to argue this stuff to begin with. As long as the meaning "to write/type HTML and CSS" was conveyed, does it really matter? To look at a document as big as this and latch on to the code vs. not code distinction (an arbitrary one depending on how you look at it) in the title is to miss the document's greater value.
I think it does matter because code makes it sound complex, wheres markup explains what it actually is. I don't think everybody in this world should know how to program ("code") but I do think every person in this world should know the concept of markup, because essentially that's the same thing as knowing how to structure text which is just as important as spelling and grammar.
Does it pass the conversation test?
You're sitting in a diner and an old acquaintance walks in. Conversation begins and you ask what he does for a living and he responds that he's a "coder". You ask, "Oh? What language?" to which he responds, "HTML."
Not really. It's simply a reflection of how terms get tossed around where they are incorrect, such as the much over used "engineer". There are "sanitation engineers", "software engineers", and "civil engineers", and it's possible that any of these are truly engineers. It's also possible that they are not.