This is not as deadly in the modern game with many cards that want to go to the graveyard, but during the Duel Monsters era, it was banned for giving players too much advantage
This takes a second to quantify
Thorton is useful for getting rid of one-of Pokemon like Squawkabilly ex , which is only useful on your first turn
BT13-013 C Digimon Lv.4 BaoHuckmon Color Red Cost 5 DP 5000 Digivolve Cost 1 Red 2 from Lv.3 Form Champion Attribute Data Type Dinosaur Card Text 1 [Effect] [Your Turn] When you play a Digimon with [Sistermon] in its name, this Digimon may digivolve into [SaviorHuckmon] in the hand for the digivolution cost
"06 - Amy" + 1 "Super Shadow" When this card is Synchro summoned, Banish all cards from your opponent's graveyard, and this card gains 300 ATK x the number of cards banished by this effect
Enchantment - Saga Enchantment (CTRL to add secondary) Instant Mutational Advantage Permanents you control with counters on them gain hexproof and indestructible until end of turn