The practical concern for my colleagues and me is that we're OS/kernel developers for an operating system that isn't currently supported. I had to fight these kind of problems to get java ported to our OS, and a coworker had to do it for rust, which was much much harder. And he did end up having to start from one of the earliest versions and compile nearly every blasted version between then and now to get the latest. It's a royal pain and a major time sink. If there were a viable rustc that was written in C or even C++ at the time, we could have been done in a few days. Instead it took months.