Youre unlikely to run out cards playing Black
Ink Types Lorcana decks must contain only one or two ink types
Until now, Party decks in Commander have lacked a great option to lead them
That means that, even in mill decks, being able to actually threaten life total is still a large way to win the game, as the actual mill kills won't always come, but Consuming Aberration beating people to a pulp is always a reliable way to close out games with a mill plan
The mechanic saves you from really having to cast self-mill spells at all: you just mill a little to get them into your graveyard, then start replacing draws for free chunks of three, four, or five cards flipped over from library to grave
Black and Green Make Jund Now looking at black as the secondary option, black is definitely more creature focused, and has some a good deal of removal as well