2. It is tiny
3. It is quite power efficient
4. It has GPIO pins, which make it usable for experimenting with hardware.
5. It has a great community (you can easily find many projects for it, and there are some great OSes available, which run nice educational software)
6. It is cheap
All of this makes it fantastic for education and as a gadget. The whole point of the raspberry pi is to be unlike other computers. You can set it up as a server, but this is not its main purpose.
The Dell Optiflex FX160 probably outperforms the pi at all measures, but it is just stupid to compare it to a raspberry pi, because it has none of its unique points which make the pi a good choice in the first place.
Now, there are actually some better raspberry pi clones out there. For those products, a title like this might make sense.