It’s very hard to do tags in the physical world. You need to stick different colored post-its to things and do a full table scan (with your eyes) any time you want to process all docs of one tag. Or you cluster things together depending on similar colors.

Hierarchy is easy in the physical world.

But what is crazy is since the dawn of computing we can store data however we want and project it however we want…and yet we still use hierarchy for file storage…like we still just have a filing cabinet of manilla folders.