Thats the thing with Scala, they are solving important problems. It is not spending time on useless problem like performant build system. I mean code is gonna compile eventually, if not today maybe tomorrow. But complex problem like described above will not be solved unless someone make a decent framework for it.

In the last 10 years every team/company I have been working in had to deal with at least one of these problems. Good for you if you only ever have to work with single threaded applications, but for most of us the reality of modern software development is different.

It definitely is. You can even see it by looking at how the languages market themselves, claiming to make concurrency easy etc.