Then the hiring firm is a group of fools best avoided.
Tools change like fashion. What is "hot" today will be nearly frowned on in 5 years and forgotten in a decade or so. In 20 years the fundamentals still matter, the tools, not so much (Pascal? Powerbuilder? Win32 in C?)
A smart developer can learn any tool. Hire for aptitude, not today's toolset.
I agree. Of course, there is a "spin-up" time and we prefer to select the competent candidate with skill in our tools vs the competent candidate with skill in a different tool; but absolutely a competent developer should be able to adapt to any environment.
Interviews can help accommodate this by allowing the candidate to solve a coding test in a language of their choice, while also inquiring about the candidate's learning plans. (Want to make sure they are willing to adapt to the team's tools and not try to force the team to adapt to them!)
I took a job once where the code base was in a FORTRAN-derivative language. I had never used FORTRAN or anything like it. Not a problem. I studied the code. I studied the docs. I figured it out and did the work. I would expect nothing less of any other competent developer.
Another job had a toolchain based on NodeJS on the server-side. Never used NodeJS. Not a problem. Studied the code. Studied the docs. You know the story.
The key skill is a developer's willingness and ability to learn the tools that are desired for the job at hand, and to accept and learn new tools when the time is right.
Tools change like fashion. What is "hot" today will be nearly frowned on in 5 years and forgotten in a decade or so. In 20 years the fundamentals still matter, the tools, not so much (Pascal? Powerbuilder? Win32 in C?)
A smart developer can learn any tool. Hire for aptitude, not today's toolset.