Yup, there's Skyrim (which has a much shorter main questline than Amalur by the way), there're BotW's, Xenoblades('s), and there's the rest, which are all shorter than Amalur content-wise. So we can count other games, sure, but that doesn't in any way make it a non-valid point, that it's one of the longests open-world ones
¯\_(ツ)_/¯