The point is at minimum, you get multiple annihilator cards attacking at once and this comes late enough to see the best creatures available from most decks
In 60-card Constructed formats, turbo-fog decks have found success in the past
Its the ultimate trinket card and slots into an absurd number of fiddly artifact decks
Much like Kozilek and Emrakul, only 250 copies of these spectacularly illustrated borderless cards were made, and due to them being Eldrazi titans, it makes perfect sense that all of them would be worth well into the thousands
So far the Sphinx has only attracted a ton of kill spells when he hits the table so I'm not sure if he's worth keeping in.
Taking a random one-drop wont stop them from casting two more, and they have enough game-winners that discarding those is rough even when the spent mana doesnt just mean you lose to 1/1 beatdown