Let's be honest -- people only use what everyone else is using because it lowers the bar to getting hired to 90+% of programming jobs.
I can count the number of tool-agnostic development teams that I've met on one hand. Many more have claimed they are when they are not.
If you aren't aiming for the top 10% of jobs (vague quality metric that you can interpret as you wish), then you want to have above-average knowledge of _just_ Python, Go, React, Docker and Kubernetes.
The situation only changes when high profile current/ex-Googlers (or similar) start talking about a language/tool a lot. Then the mass hops on board that train too.
I agree with the thrust of your comment but not the specifics. There are still a ton of Java and JavaScript (not necessarily React) jobs out there in the "bottom 90%".
And I don't think "high-profile" people talking has much effect. Paul Graham talked up lisp for a while, and I was certainly interested (I like lisps), but... there are still precious few jobs that use Lisp. Most people learn technologies that they either need currently or are in use in jobs they know of and might conceivably get.
Even at shops just hiring for Java or JavaScript, I don't think knowing them is a career advantage. They don't make you more hirable than you would be otherwise. That's really the only reason I left those out.
Paul Graham, while a thought-leader of sorts, isn't generally thought of as someone working at either the edge of tech or in large-scale systems. That's why nobody wants to chase the tech he's using vs what Google/Facebook/etc are.
I can count the number of tool-agnostic development teams that I've met on one hand. Many more have claimed they are when they are not.
If you aren't aiming for the top 10% of jobs (vague quality metric that you can interpret as you wish), then you want to have above-average knowledge of _just_ Python, Go, React, Docker and Kubernetes.
The situation only changes when high profile current/ex-Googlers (or similar) start talking about a language/tool a lot. Then the mass hops on board that train too.