Originally Posted by
Qualia
In *any* community, not just WoW or Blizzard-related franchises, Word of God is considered an official source. By definition, the latest released information from an official source is considered canon and override previous canons (unless refuted later by another official source). Just being a statement from Blizzard, or a piece of established lore, doesn't make it automatically canon. It need to be the one released most recently. Thus, being a part of the established lore doesn't matter if Blizzard later said something else contradicting to it. What is released last about the matter, especially with little to no room being misinformation, is canon, and thus the truth *until it is changed*. Arguing against it is just ridiculous.
I regards to the "Death of the author" trope: Keep in mind that it was about interpretation and the author's intentions. It, however, was not about whether something is canon or not. "There is no canon" is a misinterpretation of the trope. It is basically that there are many interpretations, and the author's original intention might not be the only valid one. However, being a valid interpretation does NOT make it canonical truth if it contradicts what the author said.
For example, let's use an Old God related story - we get the bits about C'Thun stalemated a Titan, and both fell in Silithus. One can interpret it as is - C'Thun fought a Titan to a draw. Another can interpret it as mere lies recorded by Prophet Skeram, an Old God's follower. Maybe there are other interpretations, I just can't think of one for now. With Chronicle, Blizzard made the later interpretation (that it was likely just incorrect information) out to be canon. Yet, it doesn't make the first interpretation invalid, just non-canon. You can claim that the first interpretation is a valid one, just keep in mind that is isn't canon.
Another example would be the pre-Cataclysm events - there are people who argued that it was the Old Gods' deaths started those, and others claimed that Deathwing's rampage in the Elemental Plane crossed the border to affect Azeroth. Both have their own merits and are as valid as each other, but there is only one canonical truth - what Blizzard said (well, they haven't said anything in detail in regard to this matter, though).
All in all, "death of the author" is more about the validity of interpretations. One can use it to argue whether a bit of information can be interpretation as this or that, but it has little to do with whether an interpretation is canon or not.