One of the big reasons for Time Machine is to make it harder for Mac owners to lose data, either through hard drives failing, or user error. Backing up to the s

One of the big reasons for Time Machine is to make it harder for Mac owners to lose data, either through hard drives failing, or user error. Backing up to the same drive only protects against user error. Instead of displaying a checklist of things you're protected against, Time Machine is an all-or-nothing deal, which makes the interface a lot simpler. It also enables retail locations extra options to make users happier quicker: if a customer comes in pissed with a logic board problem that's the "third strike" for that computer, the support staff can simply ask if the customer has Time Machine backups, and send the customer away with a new-in-box computer without having to worry about moving drives around and migrating files in-store. Apple's vertical enough that keeping Time Machine simple saves them employee hours around the world every day.