Example: There's profiles/arch/amd64/x32/package.mask file in ::gentoo repo. Somebody (let's say Larry) adds stuff to ::guru and pkgcheck complains about NonsolvableDeps for the "default/linux/amd64/17.0/x32" profile. But Larry can't fix this important QA issue because profiles/arch/amd64/x32/package.mask in ::guru isn't respected. I believe it should be. (are there other ways to solve this problem?..)
I'm not opposed to this but this basically changes how the whole profile system works. Right now it's based purely on paths without specific reliance on repository boundaries.