> It is extraordinary claims, require extraordinary evidence, or experience/proven competence.
But they don't. All they require is for you to evaluate the claims, on their own merits, without examining the speaker for their credentials. Evaluating a claim based on the credentials of the speaker is quite exactly an appeal to authority.
> And this seem to be, reactionary.
I'm not sure what you mean by this, or how to take it, so I'll try again with more words. Nobody is claiming that the best way to get a job at a large company is to build an experience base consisting solely of pure HTML websites. Nobody is even claiming that this is a good way to get a job at such, or that it will work at all. This seems rather orthogonal to the claim that, depending on what you are building and what you are trying to accomplish, "All you may need is HTML".
What is this, if not appeal to authority?
> Try getting a Job in any sizeable company by building your entire experience with HTML and tell me how it goes.
And this seems to be, "follow the crowd".