Well it does not allow coroutines to migrate to different OS threads and handles to be shared across OS threads, but that does not mean it doesn't support multiple CPUs.
It's more correct to say that it doesn't come with that support out of the box, but it certainly does allow for it and nudges you towards a specific direction (no shared mutable state).
That has been my experience using the library, I have found that it really encourages, by means of making it the most expedient option to have write once data structures.
My use case is certainly not the common one though, so others may have different experiences.
