They also do a really sloppy job of marking why packages were installed in the initial installation media... A bunch of packages that are not critical get marked as manually installed (so they don't go away if you remove the things that depend on them). At the same time, a bunch of packages that are actually critical don't get marked as manually installed. This means that you can remove a package you don't want and then autoremove will start wanting to uninstall critical parts of your system.