Anecdote time: making yourself too specialized makes you easily replaceable too. At a previous gig, a problem dev, who insisted on only using Erlang, was paint

Anecdote time: making yourself too specialized makes you easily replaceable too. At a previous gig, a problem dev, who insisted on only using Erlang, was painted into a corner by eng at large who did not want to learn/support another language (Ruby, Python, JS, Java, and R were all over). This dev eventually got fired, as they didn't really contribute much to "the big picture". Since their efforts were so limited in scope, their Erlang work was quickly replaced using the other languages, and consumers of the results never noticed. YMMV. But that's a old standard that should probably die