[userbinator]

If we're talking about toy compilers and learning, then productivity isn't really in consideration. Having a self-hosting compiler for a non-trivial language means you've achieved the "bootstrap" stage, which is a significant milestone and really gives you a practical understanding of what's involved in developing a programming language. A compiler that is powerful enough to compile itself is on the way to exiting the "toy"/"theoretical" realm that most people who study compilers don't ever go beyond.