Paul Farquhar
Legend
No that isn't WotCs position there has always been a canon for both FR and Eberron for example, it's just that DMs have always been free to ignore it if they choose and go in their direction, but that is NOT the same as there being no being no canon.
Wrong.
That used to be WotCs position. They abandoned it with 5e.
What creates confusion is when one book says "King Zog the Mighty was king of Cormyr in 1254 DR" and another book states "Bloglov the Stupid was king of Cormyr in 1254 DR". Because then the DM has to reconcile to contradictory facts because a writer couldn't be bothered to do their research.
And this is one of the reasons why*. There is so much contradictory stuff in obscure difficult to find sources that trying to reconcile it is a fool's task.
And then the DM is on the spot to make a decision.
You're in Ravnica. A devil appears before you, accidentally summoned when the players complete a ritual. What does that mean? Can it be bargained with? How do your players react?
The DM makes a spot decision. That is the DM's job. From that point the decision is canon for that game.
*The other reason is WotC has little interest in regurgitating old fluff. The reason for this is simple and purely commercial. They don't expect many people to be willing to pay for stuff that can be found for free (even if illegally) on the internet.