If you decided to install Linux you were either a complete geek, a trained professional, or completely out of your mind. It was a fantastic time for a geek. But, it meant that unless you knew your stuff, you couldn't install Linux. It shows you a nice interface which tells you that it's doing all the work for you, only requiring you to, every once in a while, make a very simple choice, or if you're really out of luck, choose a driver. But that brought with it a rather unpleasant side effect.
Morons are now able to install Linux.
Not that everyone who installs Linux is a dumb moron, just that it's way too easy to install for its own good. And that has as a consequence something dreaded. The average security of a Linux install now equals that of the default install, because there are that many of them. Originally, people who installed Linux, knew how to secure it after an install. That hasn't changed.