Threads are a leaky abstraction, so it makes sense to explore other solutions. To cite another low level detail from you list: I don't think Rust is less usable

Threads are a leaky abstraction, so it makes sense to explore other solutions. To cite another low level detail from you list: I don't think Rust is less usable because there is no garbage collection. But keep in mind asyncio has many issues of its own, which is why I'm happy that alternatives like http://trio.readthedocs.io/ http://trio.readthedocs.io/ are possible in Python.