There's one province, I do a megaturn and I buy Mandarin and now the top of my deck is Counterfeit-Copper-Copper-Copper-Silver, followed by a subsequent hand of Gold x4 and a Silver. I dump acid on my face before ending my buy phase, then draw my next hand, using memory to know perfectly well which of my cards is which. When my opponent plays Possession, he does not get to look at any of my cards, right, he has to guess which order to play them in.
Don't tell me it's "game information" or some such, next you'll tell me he can ask whether the top of the deck is 4 golds and a silver and you'll say I have to tell him that, that's also game information I might have, but not physically see!