I generally agree, but I will point out there are more ways to get packages than a repo - sure most things come from there, but plenty of things are provided as standalone installers (e.g., .deb packages). Having something that can scan that random .deb you need to do that one thing could be nice.
Not saying AV is the fix, but if Linux is ever going to become even slightly mainstream, you need some way to keep the “normies” from hurting themselves