Why have I been using these big beefy machines?" The answer is heat. You can make an insanely powerful laptop but the form factor will eventually limit performance as the heat has nowhere to go. I'm sure it did run really well for this tutorial. Keep using it for another four hours straight and that's where you'll see the difference between a laptop and a desktop.
The other reason is cost. Laptops are way less bang for your buck than a desktop.