[..]The other day I warned allies about a barrage but they just ignored it and rolled straight through the impact area and the tragic comedy was that nobody even got a scratch because the AOE is so small and the spread is huge so it didn't hit anything. It would take something like three ML-20 barraging the same area for it to be a dangerous zone.
I'm pretty sure there's a damage reduction modifier on friendly units. You could try it out in cheatmod.
That said, the ML-20 is not in a good place now.