I was initially in a faang company for 5 years, then in a startup, now an back to a Faang-ish company as a Senior engineer. I have interviewed at around 15 companies and I couldn't help but notice that a lot of these companies have a Senior "Java" engineer or "python" engineer role they are filling. I worked in a language agnostic environment all along, and although it was java heavy, I never tied my thought around java, we used the right tools for the right problem. As a senior engineer, I think it is really important to not get tunnelvisioned into one language/framework and consider all routes. But why do these companies are so heavily focused on one language and it's quirks?

[If it's a startup it makes sense that they want to quickly develop something in the framework/language they are already using, but I have seen this in large companies as well]

Edit: Thank you so much everyone for your comments and opinions. I am not able to reply to everyone but this has been an eye opener. The TLDR is that companies prefer someone already experienced either to cut down on onboarding time or to inject an experienced developer's knowledge into a relatively new project. My real problem with that strategy is, how does a company know when to use a different technology if you are only hiring people for the current stack? This has not been properly addressed in this thread. Another thing is, why do Faang-ish companies then don't do the same? Yes they have extra money to spend and extra time to spend, but that doesn't mean that they would throw away the money for no reason. Yes they operate at a different scale, but it is still not clear to me how each approach is more stuited to their process.

Some folks have asked how do you even hire someone language agnostic? Well, we used to learn the basic syntax of the candidate's language of choice during the interview if we didn't know that, and ask the candidate to explain their code if we didn't understood it, or the DS used under the hood wasn't clear. We saw the problem solving skills and the approach, not the language.