I know, personally, at least 3 exceptionally good programmers who can't write HTML and don't know what an inner-join is. They are gifted at system design and architecture, they write code that's clean, fast, understandable, and has very few bugs, and their code is delivered on time and to spec.

But they've never written a web page, never bothered to look behind web pages, and don't know the syntax. I'm sure they'd be great if they chose to learn the syntax, grammar and elements, but they've no need.

They certainly know about mathematical logic, and almost certainly know the concept of an inner-join, but they've never dealt with relational databases, and certainly not SQL.

I'm pretty sure you can't be a good web developer without being about to write at least a little straight HTML, and without knowing the differences in use and performance of the different types of join, but even then I'm not convinced.

Just speaking from my experience. It seems to me that sweeping generalisations such as "Can't write HTML => bad programmer" says more about the speaker than the subject.