I took a pic of three .284 Winchester cases. It's the best I can do. I don't have a camera that will take good closeups. The case on the left is a new unsized .284 case. The middle is a sized .284 unfired case. The one on the right is a sized once fired .284 case.
If you look closely you can see that the new case on the left and the once fired case on the right have a tapered shoulder while the sized case in the middle doesn't have a tapered shoulder but has a slight rounded shoulder.
I assume this is what the debate is all about. I can see how this would work the brass but I have no idea exactly what effect it will have on the number of reloadings you will get or any safety issues this might cause. I will have to leave this up to those that know more than I do about reloading.