<a href="http:&#x2F;&#x2F;www.freedesktop.org&#x2F;wiki&#x2F;Software&#x2F;systemd&#x2F;TheCaseForTheUsrMerge&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.freedesktop.org&#x2F;wiki&#x2F;Software&#x2F;systemd&#x2F;TheCaseForT...</a><p>In short: because having things in &#x2F;usr is equally compatible, and makes some useful things like atomically snapshotting &#x2F;usr to snapshot all executables, mounting &#x2F;usr readonly, etc. possible.