It depends on the card and the condition
Cards like Living End, which cost nothing but are hard to cast normally, can take over a game in an instant, but this one-mana instant can stop that with ease
If youve ever watched a drink get set down next to a Commander pod, you already know why people do this
If the ground gets mucked up, it gets around needing the combat step to deal damage
There are any number of brutal combos you can execute here, including using Spine of Ish Sah as removal and damage each turn, or using Scrap Trawlers effect in tandem with Foundry Inspector and Sculpting Steel to infinitely loop artifacts in and out of your graveyard
The mono-colored hybrid mana symbols like the one on Spectral Procession count as 2 towards a cards mana value