The same question can be asked about JavaScript, but it's still one of the most popular languages in the world :) It's a common wisdom to use a language you know best for an MVP - that's the main reason it's Scala.

And it's not a framework, so you don't really need to write/read any Scala to play with it.

a) Runs on the JVM. So it’s fast, solid, well supported and has the largest array of enterprise grade libraries.

b) It is one of the few languages that lets you use the same code for frontend (Scala.js), backend (Scala) and desktop (Scala Native).

c) FP and the strong type system when used intelligently can make your code simpler, cleaner and safer.

d) Libraries such as ZIO (zio.dev) make robust concurrency a breeze. Not yet seen any other language/library except for Erlang come close.