But if it provides a really good standard library altogether (unicode, structs, enumerable, etc) with an excellent tooling and powerful abstractions (like proto

But if it provides a really good standard library altogether (unicode, structs, enumerable, etc) with an excellent tooling and powerful abstractions (like protocols), then surely yes. I can't comment on excellent tooling. Language-specific package managers never tend to be excellent, which is why I appreciate the limited scope of a tool like rebar. Again, you are overvaluing a language based on the libraries it exports, rather than on its true a priori merits. Some languages are designed for intense extensibility and expressiveness, like Forth. An argument based on laundry listing abstractions to dissuade someone from using it would be rightfully dismissed as nonsense, since it is their prerogative to define the threshold of abstraction they need. Furthermore, I've noticed that people who tend to promote languages based on the mere reductionist listing of abstractions tend to not understand those abstractions well themselves, treating it as dark wizardry. Erlang is definitely malleable to reasonable extensibility. See Erlando which adds Miranda/Haskell-like monadic patterns to Erlang.