I agree. Paul Turner at Google did a presentation at LPC in which he presented an alternative model that actually uses OS threads: https://blog.linuxplumbersconf.org/2013/ocw/system/presentat...

Unfortunately the work seems to have stalled out and never made it into the kernel. If that work actually makes it into the Linux kernel, then other languages like C++ and Rust that have more stringent runtime requirements could make uses of lightweight threading as well.