This is true. It's worth remembering why Go got it's shot though which is at the time of Docker being written it was originally written in Python. A few members of the container/orchestration community pushed to try writing it in Golang as Golang was also new and combining the enthusiasm of 2 communities was likely to result in greater success (turned out to be correct).
On the other hand Rust hasn't had an oportunity for a killer app, in fact it's main sponsor project Servo/Firefox is pretty much the opposite. It's a browser, the definition of a complex and slow moving behemoth of a project.
I attribute Rust's slow takeoff compared to Go mostly to this phenomenon.
After Docker was written in Go and started popularising containers outside of the lxc/openvz/other hardcore guys doing their own stuff directly on top of the kernel APIs then it was only natural that stuff would want to integrate with Docker and using the same language was a way to capture some of that enthusiasm. This resulted in software like Flynn, Deis and Kubernetes all picking Golang. The resulting network effect is very strong.
To some degree this is also down to the strength of the Go standard library. It has an excellent HTTP and TLS stack, encoding/decoding etc. All of this made it a good fit to write software that is fundamentally fairly "dumb" quite quickly. i.e software the mostly shuffles bytes from one socket to another.
Rust will most likely not find such a killer app so I think people need to be realistic about how long it will take Rust to find a marketshare. The big difference though is one can actually make good arguments to use Rust over C/C++ where you can't in most cases for Go. C is the largest software ecosystem right now and Rust is best positioned to take some of this market share away.