And to address your point, it's not gaslighting to say that React enables interactions that would be essentially impossible if restricted to server-side templating. But there's certainly some degree to which trendiness and a desire to attract developers into their ecosystem is driving this as well.
https://twitter.com/tobi/status/1585459224506671104?s=20&t=0...
StackOverflow Trends: https://insights.stackoverflow.com/trends?tags=ruby%2Ctypesc...
GitHub Star History: https://star-history.com/
NPM trends: https://npmtrends.com/
For specific co tech stacks:
Tech Co migrations: https://github.com/kokizzu/list-of-tech-migrations
https://stackshare.io/wikipedia/wikipedia
Company GitHub page
And HN in general, like surfacing this Shopify acquisition.
As for the JIT progress here are the stats https://speed.yjit.org/. I think they've been working on it for around 1.5 years they're definitely not done. Its not fantastic yet but almost 40% faster is nothing to sneeze at. If JS became fast why can't Ruby or Python? What you said about Dropbox is interesting, why is Dropbox the ones making the effort? They are not that big. There are huge companies running millions of lines of Python code - Instagram is a Django app and Google probably has a bunch of Python. I'd expect these companies to make the effort ...guess there's no economic incentive yet.