I think Lid is saying that if the pyramids were built without beasts of burden, then other constructions could also have been possible without the use of beasts of burden. Lid is denying the necessity of their use, not the fact that they were used.

But by the same logic you could argue that because the Chinese ancestors did not use dogs in the same way the Western ancestors did, we did not need to use dogs and therefore dogs are not deservant of a special place in society.