[Starlevel004]

> So what did they do? Move everything from /usr to / and drop the whole /usr legacy? Noooo, that would be too simple.

It's a lot simpler to merge them in a directory that can be mounted across multiple machines than have four separate mountpoints.

[kees99]

Mount-points were key to early history of the split. Nowadays it's more about not breaking shebangs.

Nearly every shell script starts with "#!/bin/sh", so you can't drop /bin. Similarly, nearly every python script starts with "#!/usr/bin/env python", so you can't drop /usr/bin.

Hence symlink.