I'll bite: I'd say that it's more that if there's no (current) way to track what the other package management system is doing on the distro (any distro, not ju

I'll bite: I'd say that it's more that if there's no (current) way to track what the other package management system is doing on the distro (any distro, not just Debian) then they can't tell what packages are installed and hence whether the distro-supplied packages can work with them...