I think a lot of people don’t consider it that much of a revelation, because the evidence for it was so strong in the books, they just take it as a given.
It’s a bigger surprise to the show watchers, but if you read the books, it more like “finally, we got that out of the way”.
Its not a matter of whether it was the most “SHOCKING” moment, its the most RELEVANT moment for the larger story... being dismissive of it, completely missing it, or belittling it shows how much of a A.D.D. our culture is...
Oh not one lost their head or got blowed up... yawn.