"The hardest work some people do is labor under a false impression." - somebody smartOf course they did. Unfortunately, some people and organizations cling desperately to whatever doctrine they first learned to the exclusion of new developments.
I wrote the proposal for my former department to transition from the PCC to rifles in 2002. As you would expect, the penetration potential of 5.56 ammunition was addressed.
Some weeks later, I stopped by a rifle training class to drop off supplies. While there I observed teams of rifle-armed officers approach a huge, largely empty auditorium. Each team dropped their rifles to the sling, drew their "finger guns", and cleared the structure. (The loaded real guns on their hips is perhaps an issue for another discussion.) I expressed my befuddlement to one of the military-trained rifle instructors. I was informed that one could not use a rifle inside a building because the rounds would go through walls and kill everybody.
To keep peace in the firearms training group, back I went to the computer to propose switching our rifle rounds to a "new", supposedly recently developed round that the FBI BRF said did not over-penetrate and would allow rifles to be deployed inside buildings. I don't remember which specific load we were using and what we switched to, but there wasn't much difference between them. The "new" round had, of course, been already on the market. An hour on the computer was a lot less time and effort than I would have spent trying to change closed minds.