This might matter if we were talking about Flames of War or Hail Caesar where there are matters of historical fact involved, but
all of this is made up; it doesn't matter whether you or I prefer to play in the current setting, the 1st edition setting or a mish-mash of all the different information together, or leave bits out. All that's required for civil conversation is for those of us who remember the old material to make it clear when we reminisce, to avoid confusion.
As it happens there's not much that can't be reconciled with a goo dose of "unreliable narrator"; for example, I could come up with a way to combine the "Orks breed in small communities in the wilderness" with "Orks breed via spores" if I gave it a bit of thought.
Years ago, the game was more open to that sort of speculation. Partly it was because there were fewer details fleshed out, but I blame the Internet, too.

You can be trying to have a nice conversation about the story you want to tell about how Ork society works, but then someone comes in and shouts you down because some crappy novel said something different. No gak, Sherlock; that's not the point.
I once played a Mighty Empire campaign over the course of a summer, where I played Undead. My Empire was a utopian paradise where the dead did the work so the living could live a life of ease. Funnily enough, we managed that without anyone once complaining that that's not what Nagash is all about, or that's not how souls work in Warhammer.