Voltron, I would not field dress a deer with the small wharncliffe blade, but I would do it with the master blade. If I am carving/whittling wood, for detail work that requires a smaller blade, I would opt for the wharncliffe instead of the master blade.
When in the woods and I opt to do it buschcraft style, I would not do a bow drill setup with a small flimsy blade to start a fire. You have to carve out a notch in the base for the spindle to get a coal, and on the upper end you have to carve a handhold to accommodate the top of the spindle. Depending on the type of wood, this would not be an easy task with a small and flimsy blade. It would take too long, and you would also risk damaging the blade.
Think of kitchen knives for example. Different types of knives are used for different tasks. I would think that people discovered long ago that a fillet knife shouldn't be made with 1/4 inch stock, and that a butcher's knife of cleaver shouldn't be made with 1/16 stock.
IMO, knives are not just for "cutting". Knives are made for specific tasks. An analogy would be to say why do we need different types of vehicles. In the big picture, yes a vehicle is made to get you from point a to point b (just as you say a knife is made for cutting). But if a vehicle was only made to get you from here to there, what is the point of having sports cars, trucks, vans, semi trucks. Different needs demand different vehicles. If a person wants to go to a race track, they aren't going to take a '75 Chevy Pickup. Just as a person who needs to haul 2000 lbs of cement isn't going to do it in a corvette.
See, now this makes sense as far as different blades, but there is no "tough task" mentioned.
Field dressing a deer with a master blade rather then the smaller one is not an issue of "tough" or "hard" use, it's more an issue of convenience. OF COURSE you could skin the deer with the smaller wharncliff. I have read stories of guys who were stuck out there with nothing but a Classic (left skinning blade in truck), and still did it.
Was it more time consuming? Absolutely.
Did the Classic break or sustain any more damage then the larger blade would have?
No.
VCM3 mentioned how scoring alum. is a tough task, and how you would use a sheetrock knife, not a Peanut. However, he then goes on to say that you would then trash the disposable blade.
That's my point. These are not tough tasks for a knife, these are inappropriate tasks for a knife. That's what the snips are for.
I think we tend to misunderstand what a knife is for. Knives are for cutting. Whether it is Rambo's knife, or a Peanut. They are not meant to pry, scrape, or drive a screw. They are meant to cut.
CAN they scrape and pry?
Sometimes. However, chances are you damage the blade.
As cnas122 said, there are appropriate knives for certain tasks.
Which means that they can handle these tasks.
Which means they aren't tough tasks, just appropriate tasks.
If we remember that it is a knife, and it is meant for cutting, I don't see what "hard use" could be.