This mortar not design to kill fullhealth squads, it design to bleed them and make them retreat. One shot and the whole squad turned to wounded, almost died mens. IF you want, you can make 2 120 mm mortars - after that you will see how tough it can be. I saw sometimes this strat, in small maps it could be effective.
Getting two 120's seems like a good way to lose quickly. They're soft countered by the LEIG which has the same range, seems to fire faster (disclaimer: I haven't checked actual game stats), COSTS LESS, lower pop cap, and actually hits what it targets.
I had a USF and Soviet try weapon team spam against me on Eindhoven last week and racked up 90 kills with two LEIGS.
In that same match, the Soviet had tried Maxim spam at first. The small arc and standard (slow) setup time of the Maxim make it easy to flank even when they have multiple MG's on a small map. Even when the player does get it down in time to shoot, you can often finish moving through the arc and not get suppressed. I haven't played 1v1's in the current match, but think that the Maxim underperforming is part of the problem.
edit
oft counter, not hard counter as others pointed out