Is there any reason for reprinting EE spells and SCAG subclasses aside from accommodating the AL PHB +1 rule?

Is there any reason for reprinting EE spells and SCAG subclasses aside from accommodating the AL PHB +1 rule? We adopted SCAG stuff that makes sense beyond FR, spells to make them more widely available

— Mike Mearls (@mikemearls) October 11, 2017

In Xanathar's Guide, we included only the SCAG elements that we wanted to make widely available, especially beyond the Forgotten Realms.

— Jeremy Crawford (@JeremyECrawford) December 18, 2017