UNDERSTAND:
Foremost, without some sort of grease, you will fry nothing. you will bake nothing. You are limited to spit roasting and the kettle.
Imagine yourself removed from modernity, standing in virgin woods with nothing but a knife, a saw, and an axe. Go ahead and get that grease. Because without it, there is no preservation beyond a few days. Literally hand-to-mouth, daily.
Sure, you can render fat. Leaf tallow from around the kidneys of the poor fuzzy woodland creatures you WILL kill and eat, just to survive - But there ain't a whole lot of fat to be found in nature.
It should give you an idea of just how precious butter is. A ready and plentiful and sustained source of grease is precious beyond all measure.