Arch wiki is precious. But the reason for quality of OpenBSD documentation is unlikely to be the same as Arch wiki's. The article even mentions the problem with wiki's. Arch wiki clearly shows signs that it is collected together by people looking for solutions. Articles often contains discussions on contentious or confusing issues. OpenBSD documentation on the other hand, is prepared along with the application source, often by the same developers. That is a much better solution IMO to ensure documentation quality.

That said, I'm happy that Arch wiki exists. It has become the defacto place where people elaborate their solutions for Linux.