That’s exactly it, and I’m surprised more people don’t see it that way. For such fiction, there will almost always be a bigger nerd that eclipses your own knowledge on any particular aspect of canon, and yet someone pays half-attention to a child’s curriculum or reads a Dawkins or Hitchens book and it’s treated as an insult to their intelligence to politely inform them of something they may have missed.
At least fanfic arguments tend to lean more civil, and are generally seen as an expression of zeal between peers who all enjoy the same thing, albeit with differing opinions on the details.
Doctrine is revealed slowly and incrementally like the unfolding of flower petals, but discipline can change as the need arises. Cremation was avoided originally because it was associated with disbelief in the resurrection.