Since the inception of the 120mm-armed Abrams tank, we have lacked a true anti-personnel weapon system.
see?
You're right. Back in the later 70s when I was at Fort Knox, our M-60 tanks had four standard combat rounds. Sabot, HEAT, HEP, and Beehive. The Beehive could be set to open at various distances and the flechettes would begin their spread pattern.
But since the M-1 uses the 120mm, only two combat rounds were available: HEAT (High Explosive Anti-Tank) and Sabot (depleted uranium penetrator--armor piercing discarding sabot). Only the coax and other machineguns were truly anti-personnel. I'm not surprised that they have again added this type of main gun munition.