With a minimal ROOT=/whatever emerge $my_set_of_pkgs, openrc does not work at all because grep is missing. Also, it is surprising bash is off by default. Reproducible: Always
The packages in the ::gentoo repository can't be expected to work without @system installed, so it's not clear what you're doing or why you are doing it / think it should be doable. If you're trying to build a blank rootfs with only a couple applications installed and no POSIX Utilities userland it is going to tend to require a bit of manual tweaking -- duplicating the work of profiles/base/packages in the openrc ebuild isn't really an effective thing for ::gentoo to do.
I think ROOT= makes it a bit of a different situation because we want to support people making minimal images with it. That said, I dare say there'll be bigger problems than openrc if grep is missing. But I'm not opposed to adding the dep for RDEPENDs if it showed up as a real issue with ROOT=.
I'd definitely like to have emerge openrc merge run dependencies, but i'm afraid it's openning a full can of worms, because, if i'm not wrong, some will prefer to use busybox's (and i think i'll go that way). #942411 is of the same vein.
I knew I'd considered this before and I couldn't think of the reason I wasn't 100% in favour of it - and you've just identified it :)
