That way leads to high numbers of boxes with vulnerabilities, which may be "fine" for non-technical folks. That's not the audience linux serves however.
I don't think it's at all clear that it would lead to high numbers of boxes with vulnerabilities. Is it clear that a Mac is more vulnerable than a desktop Linux box, if you control for for the technical sophistication of the person maintaining it? I don't think that's at all clear.
While it's not guaranteed they'll be installed, the vast majority of linux desktops get security updates, including for all normally installed applications. That's a pretty big advantage over a manual update strategy.
