I lead a team running very large scale distributed systems with almost a decade of experience and I could take a guess about what these elements and attributes mean but I don’t claim to fully know them.

I also believe I’m fully capable of googling the specification and understanding this in like 15-30 minutes, but by your definition I guess I’m a fizzbuzz failure.

You missed the entire point of the article. The point is now to know whether you know those 10 lines by heart, it's whether you can have a discussion starting from just this.

Do you know why the document starts with a doctype declaration? What accessibility tags are and why they are important? What is OpenGraph and why SEO is important? What are CSS resets and why do we use them?

If you can take a guess you're already halfway there. If you can explain what you know about them you've aced it. It's not about knowing all of the meta tags or the OpenGraph attributes, it's whether you can have a discussion about mobile design, accessibility and SEO.

I’m responding to someone who claimed this is a good fizzbuzz test which is different than the point of the article.

Could you not also Google the answer to fizzbuzz in 15-30 minutes?

You could Google solutions very easily but I suspect if you can’t do fizzbuzz you couldn’t explain those solutions very well.

I see fizzbuzz as a basic test to see if one can synthesize basic programming concepts and implement something that works. Explaining the first few elements on an html5 document is more like asking if you have definitions memorized in my opinion.