Grixis Reanimator leans on Unearth and Persist to cheat Archon of Cruelty back from the graveyard, and needs graveyard fuel for Abhorrent Oculus's additional cost and Psychic Frog's flying activation, so Rest in Peace is excellent — exiling their graveyard on entry shuts down Unearth, Persist, and Abhorrent Oculus's manifest dread engine (once the eye itself is already down, though it prevents future recursion of anything else). Surgical Extraction can strip a discarded Archon of Cruelty before Unearth ever finds it. Thoughtseize takes their Thoughtseize or a key reanimation target on turn one, getting ahead of their plan. Kroxa, Nulldrifter, and Pest Control are too slow or low-impact against a deck that wants to loot into graveyard value quickly, so they come out for the graveyard-hate package.