i have the feeling the very first optimization ( not using the VM real green thread, but something lighter that doesn't provide debugging tools) is also something you wouldn't like to have in the real world..
It is using VM green thread, just more primitive one. Just to be more like other implementations (except anode) in original article that do bare minimum to run. Also, this isn't that unusual to use just `spawn/1` for simple and short "one-off" processes.