Once their Graveyard has been established, they can use up their hand rather quickly, with no way to replenish it, and result in top decking after one or two plays
This is huge for keeping Charizards Inferno X fueled up you can build your energy reserves faster without relying only on manual attachments
However, when Takahashi introduced a card game called Duel Monsters (also known as Magic & Wizards) in the manga, it generated such a strong interest that Takahashi was inspired to change focus
While the flexibility these abilities offer is already quite powerful, unlike other Planeswalkers that may only activate one ability per turn, you can instead activate two of Urza's abilities during each of your turns
The English sets typically stay mindful of the generation that's currently the main focus, making things like Legends: Arceus cards or Omega Ruby and Alpha Sapphire cards fall under the titles of Gen 8 and Gen 6 respectively, ending up part of Sword and Shield and XY sets