For anyone who is on my Facebook and has seen my art...I work from a laptop. A cheap one at that. They aren't useless. And I can flip the argument and say I've crashed two desktops in the last 5 years because they couldn't handle the work. Desktops aren't all that is holy and good.
But, they do take abuse better. I might be able to squeeze an extra year or two out of a desktop rather than the laptop. But for someone who runs their technology ragged...one isn't really any better than the other.
For people who run music, videos, and general browsing, either desktop or laptop would work for them. The difference is just...the abuse. Very few people are willing to clean out their crap, run NICE software, and keep up with the general maintenance. Then they turn up all the quality settings and run it into the ground. Yeah, laptops don't take abuse well. But that is honestly the only real difference between a nice laptop and a decent desktop.
So if you are looking for high quality processing power, but you know you've killed your last 5 computers or so within 5 years...then don't bother with a desktop. You're still going to kill it, it'll just be a more expensive murder. If you are going to take care of your electronics, and work with what you got (rather than making it slave for you), you could get away with a laptop. But if you're just some run-of-the mill person looking to maybe play a few games, run a few editing programs, and mostly browse and never keep up with any maintenance, ever...get a desktop.
In the end, you have to find what is the best option for YOU.