The post is, "What is a big knife for?"
For me, it is to pound stakes, dig out roots, cut small braches for cooking food on, maybe chop dead saplings for firewood. Also good for poking into holes,prying, digging catholes and jamming into stumps, dead trees or cracks in rocks or old sheds as a temporary shelf or foothold. Good nutcracker, too.
When someone brings up "Rambo", suggest they watch "the Edge".
If I need to whittle, I use the appropriate sized blade, I don't use a spoon, it amuses me when people bring up needing to carve spoons. Wanting to carve a spoon, fine. But do you really need one so badly you will lament over not having a small knife to whittle one? Why does anybody need a spoon in the woods? I do use chopsticks though.
I do have small knives too, I backpack and usually prefer a thin knife with a 4-5 inch blade, as most packaged foods that I bring like bread , cheese and sausages come in about 4" wide size.