What you're overlooking is that the "LCD" on the 5D, like virtually all the other EOS Digitals, is actually a very hard plastic cover over the real LCD; it's an inexpensive part from Canon Parts, and can be replaced by the end user. The only exception to this to date is the 7D, which has a glass cover, but is still highly resistant to almost anything you can do to it. If you cracked the cover you applied to the LCD protector Canon provided, but not the Canon plastic, then the "protector" you bought didn't protect anything. I've got cameras that are showing bare metal all around the screen, but no scratches on the Canon screen cover; they're that tough.