Not at all. Most of the pyramids, and many many other burials were ransacked by graverobbers and scavengers in antiquity - in a lot of cases, even while there were still pharaohs. It's assumed that a lot of them were robbed immediately, by the same workers who built them - in fact, even as early as the Middle Kingdom, there was a thriving trade in robbed grave goods for the explicit purpose of reuse in another burial, so it's far from uncommon to find people interred with spells on papyri that are centuries older than them, but have had the original owner's name scratched out and the new one inserted. If anything, the respect shown for the Giza complex in the last hundred years or so is the exception in its history. Heck, one of the two smaller pyramids has a huge hole in the side from where a 16th or 17th century caliph tried to demolish it.

Essentially, humans have always been garbage.