I have heard arguments over the years along the lines of this:
We need to use programming language X because developers proficient in this language are easier to recruit.
I was, presumably, a Java developer for roughly 18 years of my career before 2015. At a minimum, I used Java and SQL for my work, which was considered an essential requirement. I used UNIX shell scripts for automation. If I ever restricted myself to being exclusively a Java developer, I had to know at least 3 programming languages just to get my work done.
I believe that pigeonholing myself into a single programming language or a single platform would have been detrimental to my career, and I am glad I never fell into that trap. Where are, may I ask, all the Deplhi developers?
Perhaps, we shouldn’t be recruiting developers based on some single technology they know but on what they can learn and apply in the future. A generalist developer that can pick the right tool for a given taskand articulate why they made such a decision is a lot more valuable than a specialist.