Apple's having given us Time Machine doesn't negate the fact that an indeterminate percentage of the world's current and potential Mac users, you (Addendum: grelber), as has been already been noted, included, has been disenfranchised and/or inconvenienced and/or forced to spend extra money for something that may, in some circumstances, be considered useless.
I've been a computer owner since 1977, when I got my first Radio Shack TRS-80, and if there's one thing I've learned in that time it's that a backup hard drive is *never* useless.
There are two kinds of computer users in the world: those who have experienced a catastrophic loss of their hard drive, and those who will. Anyone on any computer of any kind whatsoever needs to understand that if your data are important to you, a backup system is not optional. You *will* lose data if you don't have one; it's only a matter of time.
I actually keep two--one that I do frequent backups onto, so that if my hard drive takes a header I'll never lose more than a day or two's work; and one that I do less frequent backups onto, so that if I accidentally delete a critical file and I don't figure it out for a week, I'll still be able to recover it.
