the thing is that bulletins are complete shit if you can't stack them. it's just a shitty system because THQ wanted something for players to collect.
Yes, all this system need the overhaul, but now some stackable bulletins are way to powerful, and if you was lucky enough to get them they will give you unfair advantage.
I think any armour bulletins shouldn't be stackable, actually any kind of same bulletins shouldn't. It isn't good for balance. I personally have 3 panzer 4 armor bulletins, and 3 shreks discount, and 3 su sniper vision bulletins, and 3 ML-20 accuracy, and etc, is it fun/cool - yes, is it good for game - no.
In 1945 the Soviets began to fit mesh spaced armour to the side of their tanks and assault guns to give added protection against weapons such as the Panzerfaust. This quickly became known as bed spring armour, due to it looking like the sprung metal base of a bed. It's quite useful against HEAT, cause it activates particle stream far from armor.