cards like fling mtg New Bloomburrow Uncommon Creates Competitive Deck! Fling deals damage equal to the sacrificed creature’s power to target creature or player. Fling | Dark Ascension |

Why not double it

The same holds true against other creatures that can achieve a high toughness like Ledger Shredder, Murktide Regent, Tarmogoyf, Construct tokens and the like

This is the quintessential "slippery slope" where one seemingly reasonable argument opens the door for another, and another, and the next thing you know we might as well just be playing with 20 life, 10 infect, and no "special treatment" card list

Pre-War Formalwear is a staple of Legacy Death and Taxes decks as a way to keep your creatures around since the majority of the deck are creatures with a mana value of three or less

Depending on build, that payoff can be combat-focused (for example Craterhoof Behemoth/Finale of Devastation) or spell-chain focused.