White Plume Adventurer was also an interesting ban target because for the first time in years, a stompy deck utilizing Ancient Tomb and City of Traitors was on top of the metagame. While stompy decks have historically always been worse than fair and unfair blue decks, 2018 was the last time when Moon Stompy won a major event (Legacy Grand Prix Birmingham) in a meta heavily dominated by previously mentioned Grixis Delver and 4c Control.
The main reason why the stompy archetype was always behind its stronger competitors is the missing of card selection and card advantage.
Usually, once stompy decks empty their hands and their threats are being dealt with, the deck relies heavily on top decking without any form of library manipulation to close out games. While blue offers perfect deck manipulation almost the entire game, stompy decks tend to not keep up with the premium package of Brainstorm and Co., making them overall inferior. The only exceptional stompy version which can keep up in card quantity and volume is 8-Cast, which became a relevant deck since the addition of Modern Horizons 2.
The initiative mechanic introduced a new way of staying competitive. Once the initiative creature resolved, Initiative quickly snowballed through the game by enforcing strong effects, regardless of the board being cleared in the meantime. With the help of mana cheating lands and artifacts like Ancient Tomb, City of Traitors, Chrome Mox and Lotus Petal, the deck consistently presented an initiative creature from turn 1, especially with aggressive mulligans and through Force of Will due to the help of Cavern of Souls.