M:N threading may make sense for a higher-level language implementation like Erlang or GHC where you have a runtime in charge of things anyway and can reap bene

M:N threading may make sense for a higher-level language implementation like Erlang or GHC where you have a runtime in charge of things anyway and can reap benefits with initial stack sizes substantially smaller than a single VM page, allowing creation of millions of threads. But since Rust is intended for runtime-less lower-level programming it doesn't make any sense here.