Or maybe Apple doesn't want to pay warranty claims (or, worse, lawsuits) on stuff that's burned up by cheap third-party power supplies and cables that are millimeters away from a fire at any given moment.

http://www.righto.com/2016/09/why-you-shouldnt-use-cheap-mac...

http://www.righto.com/2012/05/apple-iphone-charger-teardown-...

http://www.righto.com/2012/03/inside-cheap-phone-charger-and...