G'day theonew
But in order to be an effective chopper of wood, in my experience, you need a "hatchet" that weighs close to two pounds. Whereas an 8 inch silky saw weighing 9 ounces coupled with a sturdy 4 - 5 inch FB knife that weighs around 6 ounces comes in at less than half the weight and has greater overall efficiency.
My GB mini weighs 10 ounces. One ounce heavier than your 8 inch silky saw. Not much of a difference
I don't carry a hatchet for its chopping power. If I need to break up wood for a campfire I use the leverage generated by using the fork in a tree to quickly and easily break up limbs. Any that don't readily yield to this technique get fed onto the fire as they burn. I find these two techniques to be the most efficient and calorie saving methods I know of :thumbup:
For this I would use a rock or a baton.
I guess if you don't have a better tool available then you would have to use whatever's at hand, but IMO a rock is a poor substitute as a hammer. With regards to using a batton, I take it you square off one side of the batton first. Being able to use the hatchet as is saves me the time and effort needed to find and shape the batton.
For this I would use the knife
Me too

.
However, the OP was asking why people chose a hatchet over a saw. This example was raised to show the additional versatility of a hatchet over a saw, not a knife :thumbup:
For this I would use the knife or perhaps coals from the fire.
IMO, choking up on a small hatchet gives greater control when shaving wood than using a 4"-5" fixed blade. Give it a go, you'll be suprised.
Whilst coals from the fire will slowly smolder the wood and make it easier to remove the carbonised area, this takes
FAR longer to do than carving away the wood with a small hatchet. I know, I've used both methods over the years.
No, but a knife can
Again this example addressed the difference in versatility between a hatchet and a saw, not a knife.
To some degree perhaps but a knife would be my first pick.
I find bark is far more useful as a material if it is removed in sheets that are free from tears and holes (It's more water and wind proof that way).
When using a hatchet to peel the bark off, the additional width of the hatchet bit spreads the pressure over a larger area than the width of a knife can (unless of course your using a knife with a blade that's greater than 2 1/2 inches wide). This helps prevent the bark from tearing as it's being levered off. That's why a hatchet is my first choice for this task.
All things considered, I reckon I'll continue to bear the burden of carrying an extra ounce in weight for the additional versatility a hatchet gives me.
Bear in mind as always YMMV.
Kind regards
Mick