I am sure it was first abused, and then someone took a very coarse file to the tip.
The tip is not a regular tip for any screwdriver.
The double tapered standard shape was proven to be the strongest pattern over and over. And people were used to seeing the profile of it, so it sold in the marketplace.
Everybody used it in manufacturing.
I have reforged lots of PH screwdriver tips. Even the big ones can be done with 2 ordinary propane torches and practice.
The big ones are faster and easier with a hotter torch, but that's ok, you can still do them. And the med and small ones are closer to a piece of cake.
Set up 2 torches facing each other, and make a vortex of heat.
Whatever you hold in that vortex heats up.
Its 3 times faster heating both sides at once, compared to a single torch.
Here is another quick tip
Set up a one burner propane camp stove. Throw your driver on that running full blast, while you futz around setting up your torches, hammer, anvil, quench can, etc.
Preheat your work. Saves time when you do go to heating it for real.
yours Scott