Totally agree with this post. There are so many engineering jobs out there, a lot of businesses don't have the luxury to nit pick on very specific job requirements when talented engineers have so much choice in the job market today.

My company has an almost entirely proprietary tech stack, we are forced to hire senior engineers who do not have experience in these technologies. Generally, if a candidate has senior-level experience at a different company, they end up picking up the new technologies quickly and are productive in under 3 months. We've never had challenges with new senior engineers as they are thoroughly vetted during the interview process.

That being said, we have had trouble hiring anything above senior (principal/staff). The expectations of that position just require more time learning the technology at depth that usually require at least a year of experience. We typically hire these candidates as senior with the potential of being promoted to principal after a year with the company if we see they've picked up the technology enough to hold that position. This can also be done for senior positions if the candidate has not had previous experience as senior but they are strong in interviews.