I feel that you are 100% correct Alexander with what I've found with gear in hand, and researched about it. There were many inventors/opportunists/etc near the last year of our involvement in WWI.
(We were only involved with WWI in Europe for a little over a year)
In action, the thinly constructed 'grenade apron' was almost useless, as was the BAR belts with the metal waist cup to place the BAR butt into a metal holder. Neither worked at all in real life and few US soldiers wanted them, so there were TONS manufactured in WWI that never saw any service and ended up in surplus in huge amounts up till today. I have picked up several brand new grenade vests over the years.. All 1900's dated, but in almost new condition. I tested one apron with only four inert grenades in the top pockets and it was unwearable with only four inert grenades. The thin pockets pulled way away uncomfortably in the thin vest and it was was piece of junk to me..... A lot of US WWI gear were the same way back then...
I have had fun researching WWI aircraft, etc, but there were a LOT of goofy ideas back then that didn't work at all.