What's the value proposition of Scala?
You pay x1.5, but you get x3 output.
You get 1/10 of the talent pool but you run 1/50 of the interviews.
You can't grow as fast as with Java but you can do much more with much less. And the cost of running a company (e.g. processes, communication) grows with a number of employees.
So yeah, you won't build another Google with just Scala. But you can't definitely build a lot.