I think there was an immediate understating of what the game is about
While he doesn't benefit from the shift ability, it also means that, like Clarabelle, you are less limited in what kind of deck you place him in
Can you Blink a Planeswalker
White decks typically have far more than the average number of enchantments, regardless of strategy, and Mesa Enchantress helps you keep the action going
Alternatively, it can just be a solid buff to a deck running a lot of dinosaurs, and you can simply cast it for 1 additional mana, giving all your creatures an instant benefit
Underrealm Lich Self-mill is generally the first step in your gameplan, so its very impressive that a five-drop made it this high on the list