That is 1 pixel of hp bar left, 1 pixel.
The HP makes no difference at all. It like expecting to kill medium Tank with small arm fire because it has low HP. Hit either penetrate or not.
Also if spamming nade into bunker, fox nest is promoted blobing then how many nade requires to take down 1 bunker ?
Blobing is easy, huh ?
There are a number of grenades that do bunker damage consistently, hell satchel/heavy gammon bomb even one shoot them.
And commandos can blow them up.
Point here that is mainline infatry can do everything there is little reason to build anything else.