It's managed through a central interface but does not require you to use the same installer for everything. This makes sense!
Yes, isn't it nice? I enjoy being able to use aptitude, apt-get, gnome-apt, or dselect, as well as simply clicking an icon in KDE, to install packages.
But the point was, it was harder to get things done then, and it's harder to get things done now, comparing Linux to Windows.
For YOU. Not me, or any other person who uses free software and Unix for its rational benefits over the alternatives. Not everyone is a dogmatic or a zealot; they're just the ones that speak the loudest.