Is it that they couldn't or haven't? It's obviously capable of compiling code, but with the state of compilers today (impressive backends, etc.) does it make s

Is it that they couldn't or haven't? It's obviously capable of compiling code, but with the state of compilers today (impressive backends, etc.) does it make sense to have a three-stage bootstrap (minimal C → mini-go → full-go → optimized-full-go) at this point?