Even if I couldnt, a four-color commander gives you the ability to play all the cool cards you could want within his color identity
many formats have big creatures like Hullbreaker Horror or Niv-Mizzet, Parun lurking around
While landfall decks will love this effect, it's more of a way to ensure you have all your resources available to you instead of constantly losing them to the graveyard as you mill yourself throughout the game
Dig Through Time would give even more power to blue-based combo decks, further pushing the formats linear strategies
Its art and phyrexian mana add to this effect, and it makes for a somewhat intimidating card that you cant help but desire to tap into
For the sake of flavor some of the choices are not optimal, but are (usually budget friendly) alternatives that fit greatly the Simic Elf tribal theme