This was from Alter Ego #158, Roy Thomas said he asked how George Lucas how he was going to be able to keep all of the stuff together. As you can see here, Lucas said "What happens in the movies is gospel. Everything else is gossip." And I think that actually highlights what Disney fucked up about their Star Wars stuff.
The movies by JJ and Rian barely give you much information. The individual OT and even the PT (even as bad as it was) films still gave people enough info that they still felt self-contained and were in an expansive world, even when there were questions raised.
With the new films they're arguing that you need to get all the supplementary material.