Both of you, deux and Hongwelbing, are misinterpreting my response. I don't mind the "potential" lore existing, but it has the same drawbacks as running a game in the "real world", when it has such a vast history and events some people can't possibly remember. "Learning the lore is teh hard" is not an argument, it shouldn't be a requirement to read 20 shit books, ever. The rulebook and maybe the DM/player guides should be more than enough, everything else is voluntary flavor.
We don't really disagree in practice, but I think that such things should be settled at the table rather than through a dismissal of the canonicity of such works. Pedantic players should stick with pedantic DMs, non-pedantic ones with non-pedantic DMs.
The statement that the books are non-canon does nothing to anyone who wants to follow the books, and has read them, but it gives the DM dealing with an unnecessarily pedantic player ammunition to shut it down.
Here I disagree with you since such a statement negatively impacts the development of the expanded universe of a particular setting. If the books aren't canon, then there's no reason for the various writers to strive to maintain lore consistency across them (ergo this negatively impacts the enjoyment of the setting for the lorefags, whether they are DMs or regular players).
You don't need an arbitrary copout as a DM to shield you from a pedantic player if you set rulers in advance of starting the campaign which forbid such behavior (i.e. having a restricted canonicity in your worldbuilding as a home rule - if things contradict this or that novel regardless of the DM's intentions to keep true to the expanded universe, that's nevertheless legitimate as part of the DM's worldbuilding and not something up to the players to decide).