I'm not even an exceptionally talented programmer: just a competent one. Of course there are real differences between languages that matter, but at the end of the day ifs are ifs, ints are ints, functions are functions, etc.
Relevant old joke: https://www.reddit.com/r/ProgrammerHumor/comments/4k994j/if_...
That said: there are some reasonable scenarios when you want to hire someone with prior experience; for example as a first or second hire it's probably a good idea in most cases, or if you really need someone who can hit the ground running.
Case in point: a Stripe job listing I picked at random
https://stripe.com/jobs/listing/backend-api-engineer-core-mo...
No single language is named! And this specific sentence is a really great sign (unsurprisingly)
“Languages can be learned: we care much more about your general engineering skill than knowledge of a particular language or framework.”
I think that in the specific case of Stripe, they specifically mostly use Ruby (from answers I found online). I may be wrong, but I assume that not mentioning Ruby is a way to attract Python/Go/C/etc. developers that might otherwise think that since they don’t code in Ruby, they shouldn’t apply.
Your main point (re: Java) remains of course.
"We mainly use [language X], but you don't need experience in [language X] for us to consider your application" - this is a totally normal thing I've seen in many job postings.
Stripe is sometimes more explicit about it:
https://stripe.com/jobs/listing/infrastructure-engineer-ruby...
"Our most popular language in the company today is Ruby, and we are building a new Ruby services practice in support of this."
... but that job is also an openly Ruby-centric job.
You can't just go around telling people that: you are going to make hiring harder once everyone figures it out!
When you get a referral for a 10x and you're meeting at Blue Bottle you need an ice breaker; clueless community-college tier HR asking for versions of frameworks makes for an excellent one!
It doesn't matter :-) such organizations aren't good at finding out if someone is "talented and bright people with mastery of CS and SWE" in any case
Good organizations hire talented and bright people with mastery of CS and SWE fundamentals. Bad organizations think "oh we use Java, better hire Java programmers". Really bad organizations think "oh we use JUnit, Spring Boot and IntelliJ, better hire people with experience in JUnit, Spring Boot and IntelliJ"
One of the strongest signals of how good an engineering organization or a tech team is how few specific technologies they list in their job ads.