It is always a mystery to me that I cannot find loads of info on this subject. I always get lots of options on how to do it and much of it is fascinating but still I cannot get a real answer as to why.
We got a couple of folks who do it for economy and a couple of "don't do" for disease prevention , and one interesting answer for cutting to help the spud rot which in turn benefits the new potato.
I have tried several times to get an good clear answer on this topic. I have sat in meetings with gardeners and asked and still I get what folks do but not why.
I have come to the conclusion that this may be the same as the Jewish question " why do you cut the end of the brisket before you cook it?" Mum did it, lets ask her, Grandma did it , lets ask her, Great Grandma did it lets ask her... Great Grandma explained because her pan was too small and it became a habit.
So I figure that this is the case here, no one really knows why they do/don't do it, they always have, their Dad did. their neighbours did etc etc.
I doubt we will never truly know.
XX Jeannine