For several years of car camping, I owned a couple large knives because I was intrigued by them. I never could figure out a use for them, so they sat around as safe queens.
Now that I do more hiking, backpacking, and non-car camping (now weight is a concern) I use a large knife ALL the time. When doing these types of activities, I like to have two knives. One small fixed blade (around 4 inches) and one large fixed blade. I usually have my folder too, but that is just habit because I have that everyday. For doing your firestarter chores, the big knife can be enough to chop or drive through dead wood. But, I usually find it is pretty easy to also pack a small, light portable bow saw, such as the sawvivor, or the browning or gerber version. These can be used to cut up larger pieces of deadwood, and the large knive can be used for batoning into smaller, useable pieces for starting the fire. Or when it is wet or snowing out, getting to the center wood is critical to get dry wood anyway. This method is lighter than a hatchet, more precise (you set the knife down where you want) and is actually more efficient. You use small controlled blows. The larger knife also does well for preparing the tinder, shaving bark, making firesticks, etc.
That is the more common use, for me anyway. More uncommon uses could be survival type situation. Having a knife with enough chopping force to build a shelter is the first to come to mind.
Doing all this frees up my small knife for more detailed and less strenous work.
I also think it is important to use your wilderness skills, such as firemaking in wet snowy conditions, with the gear you have on you all the time. This is the stuff I take with me all the time. I do not have a hatchet or ax with me all the time. If you preference is to not carry stuff, and run nekkid, that is cool, so you should practice that way
Now that I started using my large blades this way, I do not have a single safe queen. If it is too pretty, or I do not think it can stand up to the useage, or if its ergonomics do not work well for my purposes, I have sold it.
Brian
