There's nothing that limits rpm/deb to distribution. Anyone who publishes a tarball with software, can publish rpm/deb as well. Many do.
Hence my "or otherwise bundled..." note.
But you're still only thinking in terms of packages that are bundled and installed via the system tool. Anything not installed via that tool can typically do whatever it wants if its scripts run as root, and anything that is installed via that tool typically won't be aware of anything that wasn't and will happily write all over it with no mechanism for backing up what was there before or reverting a breaking change.
The point is that relying on some voluntary convention like this isn't good enough. A modern OS should enforce mandatory restrictions on all installed software. We should be able to do things like checking exactly what is installed, or uninstalling something unwanted with or without also uninstalling any now-unused dependencies or any configuration data, and we should be able to do these things reliably, safely, and without any requirement for the software itself to be "well behaved" in any particular way.
Hence my "or otherwise bundled..." note.
But you're still only thinking in terms of packages that are bundled and installed via the system tool. Anything not installed via that tool can typically do whatever it wants if its scripts run as root, and anything that is installed via that tool typically won't be aware of anything that wasn't and will happily write all over it with no mechanism for backing up what was there before or reverting a breaking change.
The point is that relying on some voluntary convention like this isn't good enough. A modern OS should enforce mandatory restrictions on all installed software. We should be able to do things like checking exactly what is installed, or uninstalling something unwanted with or without also uninstalling any now-unused dependencies or any configuration data, and we should be able to do these things reliably, safely, and without any requirement for the software itself to be "well behaved" in any particular way.