That's so rare it's almost a myth. I absolutely let my pipes dry before reassembly and have had only three problems in nearly 50 years and hundreds of pipes. And all 3 were solved by letting the stummel dry longer.The shank is likely to change shape if you dry the pipe with the stem removed.
Wood is a highly unpredictable organic material.
Briar is very stable. If allowed to season before carving briar will return to shape after getting a little wet.
We had a member here, during the pointless row over water cleaning, who submerged one of his pipes in water for several days to see what would happen. After leaving it submerged for several days he fished it out of the water and let it dry for several days before trying to attach the stem back on. The fit was spot on.