In the end one they lose decisively and bloodlessly when its ruler switches sides, and another ends up under the control of a handful of defectors to their side who arrange to be the troops holding the city after secretly signing an alliance
Some popular forms of Exodia use Appropriate, Heart of the Underdog, and so on
This strategic depth makes the deck both engaging and challenging, rewarding players who master its intricacies
The second is more short term, based on the fact that UW Flash and GB Delirium currently make up about 50% of the Standard meta, which is a historically high metagame share, and cards like Archangel Avacyn, Spell Queller, and Emrakul, the Promised End have the ability to invalidate entire archetypes all by themselves, especially in our current answer-lite Standard