Red-Green is all about playing big, stompy creatures and other expensive spells, with extra payoffs for casting anything with a mana cost of four or higher
You have won or lost that game way before you get to the five count
For four mana, 2GW, she gives us everything we need for the new mechanic: a +1/+1 token on a creature and an extra card once Coven kicks in
They are more like a way to milk a bit of extra value out of your stuff as you progress from making it to sacrificing it
MTG games are at their core about resource management
Though exiling four cards a turn sounds like a lot of your deck gone, lets do the math: 100 cards, minus the commander, minus your opening seven-card hand, minus four draw steps by the time you cast this, leaves 88 cards in your library