Not sure why; corryvrecken and oogie are both part of the standard lineup. Ardbog certainly is limited and pretty much globally **** out. I'll sell you my spare bottle for a million quid :-D ...........it's very, very good.
My view: Ardbog is best, then corry and then oogie. Bare in mind you're comparing 3 of the, potentially, best whiskies in the world. 4 if you chuck in the ten year old. Bottle for bottle Ardbeg is probably the best distillery in the world.