FWIW, an inefficient but working product is pretty much the definition of a startup MVP. People are getting hung up on the fact that it doesn't beat gcc and clang, and generalizing to the idea that such a thing can't possibly be useful.
But clearly it can, and is. This builds and boots Linux. A putative MVP might launch someone's dreams. For $20k!
The reflexive ludditism is kinda scary actually. We're beyond the "will it work" phase and the disruption is happening in front of us. I was a luddite 10 months ago. I was wrong.