Another factor at work is the use of rolling updates to fix things that should better have been caught with rigorous testing before release. Before the days of 'always on' internet it was far too costly to fix something shipped on physical media. Not that everything was always perfect, but on the whole it was pretty well stress-tested before shipping.

The sad truth is that now, because of the ease of pushing your fix to everything while requiring little more from the user than that their machine be more or less permanently connected to a network, even an OS is dealt with as casually as an application or game.