Yeah, but retconning in the EU has gotten so far out of hand that it's become a massive coronary of a joke.

Take the post-ROTJ Marvel comics for example. Those stories outright declare that the Empire swiftly collapsed following the Battle of Endor, leaving only a few remnants here and there. But, more-or-less beginning with the Thrawn trilogy, the later EU in the 90s depicted an Empire that stayed strong following the Battle of Endor, only collapsing several more years of conflict with the Rebels. These two takes on the post-ROTJ Empire don't mesh at all, but that hasn't stopped the losers who run the EU from shoving round pegs into square holes and declaring it all as "canon".