I think you've mentioned a valid reason why some older but untouched guns show up now and then. Their previous owners bought them for protection, and they spent all or most of the time in nightstands or dresser drawers.
Such was the case with this beautiful Model 67. A neighbor of mine died last year at the age of 100. His estate executor knew I was a "gun guy," and showed me this gun. On examination, it appeared brand new in every respect. He had purchased a holster and a box of ammo for it; they also looked new. The holster had no internal scratches that would show use, and the ammo box was still completely full.
I was offered the gun at a substantial discount from the appraisal estimate I gave, and it was an offer I could not refuse. I popped the sideplate on the gun, and it was completely dry inside. A proper lube job was all it needed.
Roy Jinks told me the gun was shipped in April of '78, and I believe my neighbor probably bought it new at that time.
It's sad, perhaps, but I think it's entirely possible that many LNIB specimens come from the estates of folks who bought them for "house guns" but never bothered to try them out...
John