What is the point of using a diamond shape vs. flat/parallel sides awl?

I apologize in advance if I am missing something fundamental in my question but...let me explain. Here is a diamond shape awl 🔶. Let’s say needle A (flesh/wrong side) and needle B (grain/front side). In Philip stitching video he show that A starts the course and needle B goes over the top (North point) for the casting on the flesh side. Why do we then need the East/West points of the awl and make a bigger slit in the leather than needed? If a pricking iron marks a 45 degree straight slit / then why not do the same with an awl? This would imply that the awl should be flat/parallel sides, sharp point with sides width = to 2-3mm or match the pricking irons used. Also, I see tapered edge awl blades too. I just think those are garbage because, unless you stop at exactly the same spot after puncturing leather, it will create inconsistent sizes of holes.

So....when pricking irons alone are not enough, why not just use a flat/parallel sides/sharp point awl? This would also make the sharpening way easier.

Another part of my question, has anyone tried to flatten out their diamond shape awl (east/west sides) with a whet stone or diamond plate?

Thank you!