I understand where you're coming from, but I strongly disagree.

I've worked with multiple living counterexamples to your point - they only knew one language (sometimes old and non-maintained), but they could blow the next whiz-kid out of the water in terms of logical thinking and its application to software development.

IMO the only requirement to being a "programmer" is "programming", and restricting it any way beyond that hurts the field.

The guy that's been doing systems programming in C++ for 10 years should probably be considered a "programmer" despite not knowing the latest compile-to-js language of the week.