[icegreentea2]

These old techniques come from a time with completely constraints. Modern techniques are generally all about creating uniformity as far upstream as possible to them deploy cheaper labour/logistics systems/automation downstream. Think about modern masonry. The "bricks" are uniform, the mason man knows exactly how they can be shipped, moved around the site, and individually placed. Concrete mixes are standardized as much as possible and the optimized so that the man with the trowel can work as efficiently as possible.

Working with off cuts/minimally processed stone is harder. You need to be able to manipulate a greater variety of shapes and sizes. Stuff doesn't stack. It takes way more brain and finesse on the work site to make things work well.

These ancient methods are in many ways much more complicated (not simple) than modern methods. But they are complicated in ways that we're just starting to be able automate well (computer vision systems to sort/group/place irregular blocks for example).