As I mentioned before, one of the risks of a ramp deck is that we draw all mana and few finishers, and cards like Harmonize and Primal Command join Hydroid Krasis to help fix this problem
Simic can rarely make relevant plays before turn two, which gives faster strategies like Boros Energy, Izzet Prowess, and Izzet Affinity a chance to pressure the board before Simic can get its engines going properly
It also rewards you by stealing cards from your opponents decks when your vehicles connect for combat damage
The Destined Thief, however, has more upside
The king of vermin, they are responsible for not only spreading disease but causing many extinctions in the avian and reptile world
That second ability after a flip can just end the game