This has been discussed a few times here. The main concern with this process seemed to be that cutting the edge opened the outside seal between the CDs layers. It was suggested that this could lead to diminishing the lifespan of the CD. This is all speculation of course and no evidence was provided although it seems to make sense.
The supposed benefit is that the edge would be true to the center hole which should improve balance of the CD in the transport. The reduction of wobble would make it easier for the laser to read the CD accurately.
I'm paraphrasing and have no actual experience with the machine.