Of course. I should have written that programming mastery, which includes a good understanding of how to use programming languages, is necessary but not sufficient to achieving "senior" status, or building a long-term career in the field. A programmer who focuses exclusively on mastering languages is like an architect who focuses exclusively on mastering drafting. I would have thought this would go without saying, but more and more I see programmers define themselves in terms of languages and related tools, and even demand that their work revolves around their preferences. That's a limiting choice, not a way to build a successful career.