Every port being self-hosting is a fundamental project value in OpenBSD. The reason being that they believe every port should be useful and functional, not just

Every port being self-hosting is a fundamental project value in OpenBSD. The reason being that they believe every port should be useful and functional, not just a novelty. And requiring that every port be self-hosting is a way to enforce this. For example, the NetBSD project has a dreamcast port, but like most of their ports, it is crosscompiled. The last time I tried the port it would crash when put under high load for a while and would kernel panic when you tried to play audio. The netbsd dreamcast port is not functional in the sense that openbsd would like to enforce, something which is not relevant to netbsd and in no way denigrates them, but merely serves as an example.