PHEVs mean that half the time your using your battery to drag around an ICE, the other half the ICE is dragging around a battery.

A very temporary phenomenon in the evolution from ICE to EV.

Your phrasing implies this causes extra weight gain - just to illustrate, the new Prius is about 1.4t (while having decent PHEV range), while the ID4 (a similar sized EV) is 2t.