Power Matters decks specifically use effects that check how much power a creature has. High-power creatures become resources for card draw, mana, direct damage, cost reduction, and numerous other payoffs beyond simply attacking.
Rishkar's Expertise draws cards according to your largest creature's power, while Traverse the Outlands can produce a similarly ridiculous number of lands. Temur Ascendancy rewards creatures with power 4 or greater as they enter.
