I'm so tired of this Linux/Unix/Posix religious BS. Earning money with software development for 7+ years now and mostly using macOS, Suse and Ubuntu (to precise

I'm so tired of this Linux/Unix/Posix religious BS. Earning money with software development for 7+ years now and mostly using macOS, Suse and Ubuntu (to precisely name it), I'm wondering if this Posix debate is applicable anywhere outside school and Wikipedia. Of course, the recruiter is just a recruiter but with this "I know it all & better"-attitude, when the intention was absolutely clear, having no deal was the right choice for fb.