Curiously, the "Pyramid Texts" the author cites were not incribed in pyramids. The pyramids are all unaccountably blank. The oldest stonework is of best quality: mirror finishes, perfect right angles and flat surfaces cut into the hardest of rock. Likewise, the biggest one-piece stone columns and statues are oldest. Later dynasties stacked their columns.

All the oldest Egyptian construction was blank, but that didn't stop later pharaohs from tagging them with their own cartouches, chiseling off any older tags. Today, Egyptologists routinely date things to whoever was the last pharaoh to tag it.

But there must have been a real taboo about tagging pyramids, because none did them.

By the way, the reason noses and right hands of so much statuary is broken is that that was the standard Christian way of neutralizing the powerful magic they had enabled. Without a nose, they could not breathe in altar smoke. Without a hand, they could not bless.