I don't know if we have lost the knowledge though. Look at the precision work of a marble statue created by a sculptor with a chisel. That's the same ancient knowledge
really. The rocks of the pyramids were limestone, a soft rock, likely chiseled by dozens of people. I feel like some shows on tv and some books make them sound like they are laser cut or something and that they fit together within a millimeter on all sides, but that isn't the case at all. There are huge gaps between the rocks that are visible when you get up close to them. My guess is that the gaps at the time would have been filled with mortar to make them appear smooth.

I hope that this doesn't sound confrontational by the way, because I don't mean it to lol