[echelon]

"Async all the things" concurrency doesn't matter.

Javascript is not going to be faster than Go or Rust, which are increasingly taking over as web backends. (I'm writing stuff in Rust's Iron framework lately.) Or Java, for that matter.

I can serve more requests from these languages than "concurrent" Javascript.

[JSDave]

I don't doubt that you can. But in a lot of situations, as long as the slow stuff like db queries and api calls don't block, it's good enough. And that's easier to accomplish in JS.