OK, there's more than one way to skin a cat…
This is a complex subject and many methods of making rings have been published. Some are very much better than others. The method of manufacture described is designed to produce a circular outer surface, but what about the inner surface? Does the resulting ring produce a constant radial force on the bore (as it should), all around its circumference?
I'd guess that most readers are already aware of Prof. Chaddock's seminal writings in ME about piston rings. A good overview of this complex subject can be found here: **LINK** and it's well worth searching out the source documents to which the author refers.