@jk I think it’s probably a historical hangover from when people used to install their distro and packages from CD-ROMs.
It stuck around past that because every component of the system is a package and there were good arguments to be made in favour of downloading all your packages from one trusted source that also tested them on the same system you’re using, rather than downloading installers from any number of untrusted & untested sources.
I think that argument probably started to break down with the proliferation of PPAs, Flatpaks, AppImages, etc which are essentially solutions for people that want to cut out the maintainers and get their software directly from the developer like Windows users do. And now Steam just carpet bombs Linux systems with binary blobs as well.
I think the BSD ecosystem’s decision to not treat every component of the operating system as a package was probably the right call and they’ve also done a better job of managing how software is installed imho.