The attitude to treat computers as standalone PCs, governed by applications. Particularly common among MS Windows
With this attitude, the question Can I do X with my computer? only has one answer: find an application Y capable of doing X, install the application, use it. The questions Why doesn't Y work properly and
Why can't Y perform X are answered as follows: ask the manual or the vendor; if that doesn't work, upgrade; if that is impossible, wait for the upgrade. Both the world inside the PC and the world outside are dark areas; the only thing the user meets is application icons staring from the desktop.
Unix has much more of a toolbox philosophy: if you need to do X, you typically try to put together a combination of tools that will perform the task. This requires extensive knowledge of the available tools and how they work together.
The client-server model of computing is an extension of this: tools and resources are distributed over the network.
This is often confusing to PC users because they can no longer identify their computer activities with this one tangible machine on their desk. What typically happens to Sun workstations for instance is they get plugged from the network or rebooted while other people are running remote jobs on them.
The Web simplified this: with the Web it's natural to be working with computers at the other end of the globe.
It could be the universal GUI. Too bad HTML is such an abomination.