V in tine face provides a “hook” to catch roots and “hang on” during the leveraging process. Tine face makes for easy entry into soil yet provides a wider “shovelling” effect.
At one stage I was working in an area between two sheds which was less than a metre wide and I still had room to work with the prong, not like it would have been if I were trying to use my old method of breaking the soil with a mattock.
No one knows what lies beneath the soil and this is how you wreck wooden handles or bend tines on garden forks. Push into ground and if there is a rock then just take your time and lever it out. If there are hard to move roots then the V Tine "hooks" them and you can rip them out.