Because it's wrong. If you don't have physical access to your files, you don't have a backup. Someone else does, but you do not. It's like saying "I own a Lamborghini" when it's parked in a garage across the country that you're not allowed to enter and the only way you can see it is by them sending a picture. Sure, your name is on the title, but is it really yours if you can only access it at the behest of someone else?

Nevermind the fact that a backup isn't just for data loss. It's also for network loss. No Internet means no cloud. What good is a PC if it can only do work while online?

But hey, nothing has ever disappeared from the internet, right? Hold that thought while I pull up my old photos from MySpace....