I believe my Bob Douglas awl is about as sharp as they come.....but going through 4-5 layers of 9oz. is a bit of a struggle for me.
And because of that struggle, the back side didn't always look so pretty.
I find that with using a 3/64" drill bit, the leather removed is a few particles of dust at best........and the hole isn't big enough for the second needle/thread to come back through! So that's why I call the 3/64 hole, my "pilot", I still use the awl to ream out the hole to a bigger size and for the diamond shape that I want.
I've also done another experiment.......I've reamed out a line of holes with the awl, then left the work alone for the night. next day I found that the holes had closed up enough that the awl would not fit through....had to re-ream them. So the holes still close up around the stitching.
In theory, you're right about drilling removing leather....but I say, "so what?"...it's insignificant.