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Well, what Adam said is not exactly in line with what the comic portrays. HTML is not a language, so it's not about being "good", it's about actually being "compatible".
Well, you're both at least partially wrong in what you imply: HTML stands for "Hyper Text Markup Language" and that's exactly what it does: it describes how things should look, but... it has zero program logic that can be expressed in and of itself; therefore, you can't write anything algorithmic in any way, shape or form, and can't do serious work with it where computation is required, at least not without going into a deep WTFery state of abusing an HTML-capable browser.
HTML simply isn't a programming language, and it is not remotely Turing-complete.