I have “prior experience” in any many languages. But I know the ecosystem has changed to the point where someone who has recent experience would be more valuable. That would be like me (hypothetically) saying I had prior experience in JavaScript from a decade ago and I can write JQuery with the best of them.

An organization that prefers ecosystem knowledge to deep knowledge and ecosystem familiarity hints at poor planning and needing someone to "hit the ground running" to fix their mistakes.

I'd pass on such a position.

Also you talk about only having experience in a less popular language as a death sentence.

I've been only writing Haskell professionally for a decade, but I get endless amounts of interview invites for prior experience.

Out of curiosity I went through some of the better invitations interview process and had no issue getting offers either.

If anything mentioning my professional Haskell experience gets me an offer faster no matter the positions requirements.

If a company is looking for senior developers who are to serve as team leads and lead initiatives, why would they hire someone without previous experience in the technology? I’m sure you could eventually get up to speed. But the reason I haven’t had to do a coding interview in well over a decade of working at companies from your standard Corp dev jobs, to companies where they wanted a “tiger team” to lead green field initiatives, to a startup where the then new CTO was looking for someone to lead “cloud native projects” to my current job in the cloud consulting department at BigTech is because I knew the ecosystem well.

When I spoke to CxOs and directors, they wanted someone with a proven track record that could solve their problems. When I was being hired as a dev lead to lead junior C# developers he inherited, what would he look like hiring someone who knew Haskell?

How was i suppose to go from an empty git repo to a fully fleshed out MVP or later from an empty AWS account to infrastructure, CI/CD, to a fully fledged out MVP if I didn’t have prior experience?

If someone is looking to create a new iOS app. Who should they hire? Someone with iOS experience or someone with Erlang experience?