The issue is not so much with the range when used as a turn one play but the fact that you don't get complete information
It was originally one of the main reasons for the banning of Cauldron Familiar, which could be repeatedly sacrificed with Witchs Oven to cause Mayhem Devil to trigger several times, destroying an opponents board and their life total with no way to respond
Lets choose the best of all the modal spells
Slime Against Humanity isn't put into your graveyard until after it finishes resolving, so it doesn't count itself for its own effect
It gives you more casts for the Reservoir gameplan and with the grim monolith + helm ramp, Mox Emerald, and Eternal Witness, it completely locks the game out with a recursive loop
While its not hitting anything large or alive? its still going to hit the majority of mana rocks, engine pieces, equipment and Sol Rings