This is because those shops read the PG essays, and think that the the shibboleth is Python, it is not. The marker is that that someone is at the fringe and not in the middle of the flock.

I have met lots of engineers who are smack dab in the middle of the flock when it comes to tech stacks, or even _behind_, but they were more than capable. Hire for what you need. But what you think you need and what you actually need is probably not know to you.