Having Inititaitve can lead to additional payoffs via support cards like Imoen, Mystic Trickster and Safana, Alimport Cutthroat
2 Karumonix, The Rat King Toxic Rats While Karumonix, the Rat King, is a solid commander in its own right, it's much better used in the 99 since other commanders can make Rats quickly that Karumonix can back up
You might not be able to ride him to Mordor, but you can certainly follow him to victory
The reason for this is mainly that since the printing of Ragavan, Nimble Pilferer, Dragons Rage Channeler and Murktide Regent the tempo archetype reinvented itself in being primarily blue-red and making Deaths Shadow not a necessary creature for tempo shells anymore
In the case of Gambit versus Berserker, the deck generally has enough other things to do on turn two, and the Gambit is just generically more powerful after turn twoespecially in the late game
Voja, Jaws of the Conclave buffs its creatures and has card draw in the Command Zone