Dask might be lightweight internally but resorting to it just to solve a simple task that requires concurrency is not "simple".

Streamz looks nice! However:

"Streamz relies on the Tornado framework for concurrency. This allows us to handle many concurrent operations cheaply and consistently within a SINGLE THREAD."

Apparently you can set it up to use Dask to escape the single threads but that is kind of a global config. With Pypeline you can mix and match between using Processes, Threads, and asyncio.Tasks where it makes sense, resource management per stage is simple and explicit. If you have some understanding of the multiprocessing, threading and asyncio modules, Pypeline will save you tons of time.

Still, will keep an eye on Streamz, its a very nice work, lots of features, it should get more visibility.