I think if I took 10 random non diving friends and handed them a BP/W un-assembled, gave them written instructions and a youtube link, I estimate less than 50% would result in a fit I would call adequate.
So your point is that a jacket BCD is simpler than a BP/W for
nondivers? Nondivers who's total dive training consists of a sheet of paper and a youtube link? Ooh boy...
If you handed those same non-divers a jacket BCD, a reg set, and a tank I'd bet they'd have just as much trouble.
All of this hypothetical stuff is interesting - to some, I suppose - but the reality is that even if someone doesn't want to accept that a BP/W might be simpler, they are certainly no
more complicated than a traditional BCD.
The shop I DM'd at for years and did my IDC puts DSD and OW students in Halcyon BP/W setups. From 12yr old girl scout troops to former Marines and everyone in between. Over the course working with >100 students during those years I never once saw a single one struggle with the configuration. (Of course they had a bit more training than a printed instruction sheet and a youtube video.) To be clear, my personal experience in this regard (training brand new OW students in BP/W) is that they actually do far better than those who train in a recreational BCD. Weighting, trim, comfort, ease of use, etc. There are many other instructors on SB (and elsewhere) who have the same experience. On the other hand there are ZERO instructors training OW students in BP/W that I know of who have had the opposite experience. The only people who seem to suggest that a BP/W is "too confusing" for OW students don't seem to have any actual experience with OW students diving in a BP/W.
On the other hand, crewing on a dive boat and diving all over the world for the past ten years, I've seen plenty of ostensibly trained divers struggle to assemble a traditional BCD. Inside out. Backwards. Mis-buckled. Upside down on the tank. I even saw one guy trying to don his rig with the tank somehow attached to the INSIDE of his BCD.