I read the site, but still don’t get the purpose of it (obviously I get the technical challenge).
Heck if you have more than a handful of Mac's/iOS devices at home even, content cache can make a huge difference, especially when new versions or major updates to OS's are released. It also caches iCloud data so if you use iCloud Drive and/or photos on multiple devices it can also dramatically cut down the amount of traffic between your network and Apple's servers. It's pretty neat and great that Apple moved it from OSX Server into the regular OS (sharing pref pane as noted). This would be better still for sites with large guest networks and not having to have a Mac just to run the content cache.
I administer a school of 2000 students and 300 staff with a strong BYO device program. Our curriculum is almost completely online, and officially we only offer support to iPads. Our uptake has been so successful that between student-owned and school-owned class sets that 1600 iPads total have access to our network.
Picture in your mind if you will, what 1600 iPads all downloading a 6 GB iOS update over a 150 Mbit (~19 MBytes/sec) link at once might do to a network. Now compare that to a gigabit (125 MByte/sec) link to our Mac Pro and 9.6 TByte saving in internet quota.
