It’s not just about pretty screen fonts: OS X 10.12 needs to re-engineer its security.
SIP
Why can’t I install a kernel extension in El Capitan?
Strange reports of apps being damaged and needing to be replaced, and others just crashing: Apple is to blame, and is not giving us clear information.
When an app ran fine, but crashes in El Capitan, it may be SIP’s fault. Here is how to check, and more about SIP.
The Eclectic Light Company 