I certainly can't think of any value proposition Scala as a language has that OCaml (and, by extension, F#) don't.
You could say "Scala ran on the JVM," but that's backing into a value proposition based on its runtime, not what the language is (which, to be clear, is at least in part a good thing: Scala on the JVM lasted long enough that there's now Scala Native and ScalaJS, too, so the runtime reach has grown, rather than shrunk).
And it turns out this doesn't matter much... or, maybe, the growth of these languages laid the groundwork for the acceptance of Rust, which is nominally "an alternative to C ," but has practically all of the language features of ~OCaml/F#/Scala as well, leading to its acceptance far outside the "systems programming" domain.