I once saw a picture/diagram of Stihl chain. I am certain you posted it (I have been wrong before) it showed how and where the swage reduced the drive links from .063" to .050"STIHL, Oregon, etc. are big enough to spec the steel they order: can always be rolled to a different thickness.
Plus, that does not explain why they mate .325 pitch with .063 gauge drive links and 3/8 pitch with 0.050 - especially when they swage the thicker drive links down to make the 0.050 gauge.
Philbert