Part of it too is that 'canon' has become the watchword of the day. For many people, they want all of their fiction to "make sense" in a long-lasting, point A to point B narrative.
The idea of "canon" in a TTRPG is .... well, that seems kind of weird to me.
Even weirder when you remember that, historically, it has an infinite number of parallel planes with their own histories, differences, and so on. Not only is there a Greyhawk with Dragonborn, there is a Greyhawk in which all there is are Dragonborn.