An rpm just needs to add the missing scripts and binaries to your existing operating system. It doesn’t need a full mini OS image to run. So an rpm will be ~2mb while a docker image of the same thing might be 150mb. Rpm and deb packages also usually contain startup scripts so any services can be set to start when your computer starts. And they can put log files and database files in your regular filesystem without any special nonsense. They run with (generally) user level access permissions, which are much more battle tested than root permissions through lxd. And they have full access to the computer’s networking devices.

Rpm/deb packages can also install man files, command line tools, gui apps, and so on that can run directly in your operating system.