Bolt Buffers were originally designed to be a back stop in target weapons. The idea was to back up the recoil spring if and when it was too soft for the ammo used, preventing frame battering. The battering not only damaged the weapon, but could cause a loss of accuracy.
Since then, enterprising types have "discovered" the "benefit" of Bolt Buffers in virtually every semi-auto known to man, under all circumstances.
It may help eke out the last little bit of accuracy in a target weapon. With a life expectancy of 500 rounds, or so, it's just another piece to fail in other grade/use weapons. A proper recoil spring will have the same effect in a more utilitarian weapon.
That said, over the years several manufacturers have incorporated various kinds of buffers in some weapons. I believe the Rem. 1100 was one. Factory buffers are a different breed entirely.
