Also I would be interested to hear how debian has advantages in cross-building; I thought they native-compile all of their packages. Is that really the case that in debian that you can modify some existing deb source package (eg. change configure flags or apply some patch) and cross compile that into a .deb, like you can in Yocto?
And yes. I can install a cross-compiler (from the stock repo!) and custom-build whatever (not 100% of the archive is cross-buildable yet, but most of it is). And most of the time you don't care about the details, and you don't need to cross-build anything: the full Debian archive is pre-built and available on all the supported architectures (whatever you care about is probably on that list).
And there's another big advantage. Developers might be using a different-architecture machine for their testing, and it's really nice to have an identical set of installed packages and version across dev and deployment boxes, even if they have different architectures. This is actually a very common case: people develop on their amd64 laptops, but the deployment might happen on an arm, or something.