When you think about it, a regular hollowpoint is going to perform just as well filled with lint, fiber or flesh. The lint or fiber will transform the pressure created by the bullet's deceleration through flesh into an expansion force that will rupture the lead wall of the cavity just the same as anything else it passes through.
Wait, you say, the lint / fiber is compressable!
Well, yeah, that's right, but by the time the the bullet is half its length into flesh the lint / fiber trapped in the nose cavity is only a thin liner compressed against the lead walls of the flesh filled cavity. The smushed fiber has no tensel strength and no shear strength to speak of. In no way can that liner of fiber retard the normal splitting of the nose cavity and expansion of the bullet.
So why go to the trouble to put a plug in the cavity? To sell more expensive bullets to the "Rubes" obviously. As P.T. used to say: "There's one born every minute."
Just my 2c
Gerry