I am wildly guessing that Theo’s beef is more that rust uses a lot of memory (paraphrase: 640kb should be enough for anybody). OpenBSD does integration builds on a variety of different systems, and maybe Theo noticed the OpenBSD/386 build failing due to lack of necessary memory?
That seems a reasonable guess, but it brings me straight back to wondering why such a diversity of build environments is necessary or useful. And my wild guess is that it's mostly because cross compilation is still a second class citizen in most languages today. Though I guess it could be a kind of cultural expectation that you should be able to compile the whole OS on the hardware you're running it on.
My understanding is that the policy of the project is that the base system must not be cross compiled. My understanding of why is that they want to be able to fully bootstrap from base itself.
