Theres also the fact that it lives on as an infamous example of plagiarism, which definitely helped it end up so high on the list
First, it grows larger for every land in your graveyard, making it a massive threat in formats where fetch lands are common
Put a +1/+1 counter on a creature you control
Illustrated by Sadboi Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Legal Modern Legal Brawl Legal Legacy Legal Comp
Sure, you do need to pay six mana if you want to find your Azusa, Lost but SeekingAzusa, Lost but Seeking, for example, but it does offer significant upside
I like her as a "Big Stuff" Commander to wait four turns, for things like Insurrection, Expropriate and Omniscience