Google 到的一篇說明 http://www.macissues.com/2015/10/02/about-os-x-10-11-el-capitan-and-permissions-fixes/
With El Capitan, this need has changed with the implementation of System Integrity Protection (SIP). This process both locks out root-level access to core system files, and continually ensures component permissions are set according to developer intentions when updates are applied. Therefore, there should not be any need to run a manual permissions fix.