> Don't get me wrong - to an extent, some languages (especially more niche ones) drive hiring and what kind of employee you get
In my experience, the community around a given language is going to significantly influence the sort of typical applicant you get for a job working in that language. Those profile vary a surprising amount, especially for, as you say, niche languages, but also for "beginner" languages.
I have seen businesses significantly harmed because they hired what I would term language specific technicians instead of engineers. That's a failure of leader, certainly, but that failure is a lot more likely for certain languages.