One of the worst cases of this I played back in the 80s was Ultima V. To avoid spoilers, there's an obscure item that you need to get before you attempt the (very long) final dungeon, but the game only hints at its existence. If you neglect to bring it, you are allowed to play to the very end at which point it tells you that you are marooned in the final screen and cannot win because you didn't bring the item. Ultima V is still my favorite Ultima, but that part of it was ultimate cruelty!