When this also 1/1 for two mana at common ETBs, you reveal your top card
It does most of what a Fiend/Maggot does with their EtB effects and then it is better at staying in play, far better at blocking, enables raid, controls planeswalkers and is generally a pain in the arse
Want to draw another card via Archmage Emeritus
Tokens We're a Go Wide Combo deck so we want to fill our board as quickly as possible
Skeletal Vampire is moderately difficult to remove and enables some free sacrifices, so it sees play in Commander and other slow formats
But this 2 mana 2/2 does more work: Whenever one or more land cards are put into your graveyard from anywhere, it creates a 1/1 red, green, and white Sand Warrior token, but only once per turn