Because spacetime is hierarchical in that way too. I can put a thing in a box in a room, but I can't put the thing in multiple boxes in various rooms. The files

Because spacetime is hierarchical in that way too. I can put a thing in a box in a room, but I can't put the thing in multiple boxes in various rooms. The filesystem thus makes intuitive sense: we store physical objects in exactly the same way. Now sure, it'd be nice to grep through my house, but I still couldn't hang the same painting in two places at the same time.