Author is showing confused thinking, by conflating "first" with "only". Teaching a new programmer less than 2 language paradigms warps their brain into limited view of what is possible.
Even learning JS + HTML, or Spreadsheet + Bash/PowwrShell, with good instruction, should be enough to instill the key idea that languages are abstractions and there are radically different languages for different problem domains, and you should find ones that fits the applications you are interested in.
I would argue that in the context of this topic, HTML is not a useful second language. It's a completely different tool, closer to markdown or, heck, Word documents than an alternative way of programming. (I see your general point, though. Just this combo I'm not sure is the best example.)
Even learning JS + HTML, or Spreadsheet + Bash/PowwrShell, with good instruction, should be enough to instill the key idea that languages are abstractions and there are radically different languages for different problem domains, and you should find ones that fits the applications you are interested in.