The idea that a language can handle any complexity for you is an illusion. A language can automate a lot of the boring and repetitive small scale work. And it can have some of the things you would have otherwise coded yourself as built-ins. However you still have to deal with the complexity caused by buying into these built-ins. The larger a project gets the more likely the built-ins are to get in the way, and the more likely you are to rewrite these features or sub-systems yourself.

I'd say, more fully featured languages are most useful for the simpler side of projects (granted some of them can scale quite a way up with proficient use).

Now go research how some of the most complex, flexible, and efficient pieces of software are written.