It's hit or miss. Sometimes smaller firms want to be clear that they expect someone who's familiar with their stack and not looking to change it right out of the gate, larger firms usually use it because they need a 1:1 swap with some legacy position that someone has recently left.

It's pretty rare that managers care that much about a stack unless they need specific skills and aren't looking to or can't train at the given level of seniority.

Usually special skills do not imply language knowledge - but its not unusual for a job posting to look for [statically typed compiled language] and accept knowledge of any other [statically typed compiled language] as a substitute with the notable exception of anything matching [statically typed native language] or [dynamically typed scripting language].