A tree's bark is like it's skin if it were human. The bark is there to protect the tree from disease or insects. The bark on evergreen trees comes in many thicknesses and textures. A Douglas Fir tree has very textured bark while a Cedar tree has thinner bark that is like long, thin, shreds. Regardless, the bark is there for a purpose and it should not be chipped away. If you are blazing a trail through the woods, a small chip with a hatchet probably will not do lots of damage but in time, it could be an opening for a pine beetle or other insect to start sucking the sap (live blood) of the tree. How often have we seen a tree where years ago, someone tied a rope or chain or wire around the tree and it had to grow over and around that chain. It could cause the bark to have an opening that disease or insects could enter. Deciduous trees have thinner bark but it also needs to be protected to protect the tree. Carving initials or a heart with so and so loves so and so can also leave the tree open to disease.
When I was young, we had lots of trees called cascara and at that time, cascara bark was used for medicinal purposes-I believe it was for treating cancer but I was too young at the time to be sure about that. We were able to peel the bark from cascara trees, dry it, break it into small pieces and place in gunny sacks to sell to a person who accepted it to make into medicine. This was a great job for a child to earn a little money. Dad taught us how to do it and made all the contacts but he always told us not to take the bark off a living tree because the tree would die. He would cut down the tree since we had so many growing and cut them up into smaller pieces. Then we would peel the bark and he would dry and use the wood that was left in the fireplace. Doing this as a child, I learned that the bark was like skin and should not be taken off the tree unless the tree was cut down. So often, we would walk through the woods and see trees skinned of their bark and still standing. It would not be long till that tree would die. Unlike human skin, the bark does not grow back.
Some trees do shed their bark. I have a paper bark maple I planted in my back yard that does shed every year. I am sure there is a layer under that shedding bark that needs to remain intact to protect the tree through the year. We also have madrona trees around here that shed. That does not mean they do not leave a thin layer of bark under the sheded layer that will grow into new bark.
The main thing is to remember that the bark is like a layer of skin that will not renew if it is destroyed. If we want the tree to remain standing for years ahead, it is best not to damage the bark or the tree will get infected and die. If that tree is near a house, it could be blown down on the house in the next wind storm.