Let me interject with my unasked opinion:
Aa far as I’m concerned the trouble started when we stopped calling it fluff and started calling it lore (and treating it with such reverance) instead.
Oh, no, with literally hundreds of books’ worth of backstory beyond all of the “your headcanon is valid” bits, we are well and truly beyond simple fluff.
Fluff is those 3 paragraphs of contextual flavour text you get on the back of a board game box.
Let me interject with my unasked opinion:
Aa far as I’m concerned the trouble started when we stopped calling it fluff and started calling it lore (and treating it with such reverance) instead.
And Tolkien’s Legendarium is just a bunch of hastily-written bedtime stories for Chris, right?
Oh, no, with literally hundreds of books’ worth of backstory beyond all of the “your headcanon is valid” bits, we are well and truly beyond simple fluff.
Fluff is those 3 paragraphs of contextual flavour text you get on the back of a board game box.