It&#x27;s an interesting question.  One part of the the answer is that the idea is for there to be a single subtree off the root where &quot;the operating system&quot; lives.  Where MacOS 10 has &#x2F;System, OS&#x2F;2 has \OS2, Windows has \Windows, and Digital Research DOS has \DOS, systemd Linux has &#x2F;usr.<p>Of course, another part is that this is an old idea, already implemented once in the commercial Unices a quarter of a century ago.  They merged &#x2F;bin into &#x2F;usr&#x2F;bin, with a symbolic link from the former to the latter.