Why is this surprising? For years employers have included proficiency with a specific brand of tool (language) as part of their job descriptions. And in the Bay Area anyway there is often a lot of talk about being able to use any language you're comfortable with in the interview process, but in practice unless you use the language(s) in the stack you're interviewing for it's a harder sell.

I self-select myself out of jobs that have specific languages in the job listing if I can't honestly say I've used them professionally.