What is the alternative? Rust isn't there yet when it comes to IO and there are certainly no other languages that qualify and allow a similar level of control.
What about nim ? There are facilities to run an evented loop, to listen on an udp socket, can be tuned for more realtime capabilities, is compiled to C...
Nim doesn't have the same popularity. There aren't a lot of people that know the language, that makes hiring people that do difficult, it means there may be nobody at Github that does either and due to it's lack of popularity people will probably be less willing to learn it than Rust or Go.
Go is more high level and doesn't offer a similar level of control. Go is an obvious candidate that should be evaluated but it's not an obvious choice the same way that Rust is going to be and C is.
