[c7DJTLrn]

>learning a brand new language to them will still take a year or two until they approach the productivity and quality of decision-making

I don't agree unless we're talking about something like Rust or C++. Python, Java, and JavaScript are all very easy to pick up once you understand the concepts they share. I would expect any developer to at least know the basic syntax of Python for instance even if they don't write it daily.

To me, if somebody only knows one language but they're an expert in it, it indicates a lack of ambition, curiosity, and willingness to face new challenges which are desirable traits to look for when hiring. And unfortunately for such people there's polyglot experts out there that can be hired for the same price.