White is the strongest color in Magic not because it can deny like blue, remove like black, or swing in like red, but because when it does any of those things, it doesn't do such things with the facetiousness of a wizard copying a spell they learned, summoning a force, or clawing at an enemy, but with the absolute rules of reality-slamming down on an opponent to remind them that they no longer exist. White purifies the battlefield of your opponent's with absolute righteousness. That's why it's Magic's strongest color.
No creatures. Wrath of God is more than just letting opponents overplay their hands while keeping resources in reserve; it's the ability to destroy every creature that exists before Mirrodin. There simply aren't creature problems when a player lays out the wrath of the almighty. In the old days of Magic, Wrath was absolute because white is absolute.
Today, white has armies of tokens and other small, low-quality creatures, but thankfully it retains the ability to obliterate everything on the board. A win with clumsy, otherwise useless creatures climbing over the corpses of enemies with better assets may not be a proud victory, but it is a victory.
No spells. If cards like Wrath of God have one weakness, it's their susceptibility to counterspells. Cards like Orim's Chant shut down blue shenanigans. Blue is granted its obscene power because it's filtered through the eye of time's needle. Orim's Chant shuts that eye down for just long enough to disrupt blue's plans.
It's an ability that's not as absolute the others white wields. Technically, a blue mage still has the opportunity counter both the chant and the spell a white player is planning on casting. That's only because white answers to blue have to address the flow-breaking, nearly-unanswerable nature of counterspells.
No lands. There was day, before green could kill anything that wasn't a creature (and everything that is a creature with more creatures), where white was afforded equivocal destructive abilities.
White could scour the board and perform a soft, tactical reset of the game because it required ability to best create a response for a game state where both players were scrabbling for mana. If you cast it thoughtlessly, you were ruined. If you cast it with wisdom and forethought, it could hobble your opponent and win you the game.
The color's historical abilities to take no prisoners and pay its dues alongside its enemies were what made it such an uncompromising color. Today, the closest equivalent is black's disregard for life and creatures or red's cavalier attitude towards its cards.
Absolutely nothing embodies this better than Balance. Balance is rarely an all-upside card for the caster, but it's still one of the best cards out there. It might seem confusing at first, but it's because when used intelligently it's incredibly powerful, excercising powers now reserved for black, red, and sometimes white.
White is the color of power. It's the color of judges who adjudicate with absolute moral authority. You manipulate those judgments (it is a game after all), but that's the point; white isn't a color where you play a good card because it's a good card and it's in your hand or hold a card until another player plays a good card that you can stop. It's a powerful color because it requires a strategy, dedication to a plan, and the good judgment to decide when to play and when not to play.