Precision itself has an independent evolution who's development is only ever advanced for specific purposes of benefit of that precision. Why bother pushing for precision if it won't benefit you in some way for some tool, or practical benefit? In other words, that advanced precision was developed for some purpose that we don't see in the archeological evidence, but the fact that those statues and sculpture exhibit the end result of that capability implies that the ability to have that level of precision was so universally implemented in so many area's of that civilization, that methods of sculpture benefited from it without even the necessity of it.
Like the simple development of a pencil sharpener. Sharpening a pencil is the most basic thing you can do with a sharp knife. And pulling a pencil out of a sharpener reveals the point of the pencil is perfectly symmetrical, an effect of the sharpener that offers no actual benefit above and beyond what you get when you sharpen it with a knife. And yet its perfectly symmetrical, just because we have that technology available.
We gotta stop dumping on Egyptologists, because its all there for them to understand, but if we keep insulting them they'll never 'volunteer' to lose the spot light as the 'authority' of our human story.