Is that a good thing or a bad thing though?
reading the 'rampage' comments, they're removing quirks, or hacks for obscure or archaic platforms such as ultrix, hp-ux and cray. They mention using a c-library function which does the work of several functions but later it's mentioned that not all platforms implement that library function, since it wasn't part of POSIX.
As for missing c-library functions, implementing those would no doubt help porting of other software packages to a platform that lacks them. (Not possible with proprietary vendors, naturally)
So what % is actually OpenBSD specific, that won't run unmodified on current platforms using defacto standard compilers such as gcc or clang with a modern c-library?