Simply untrue. It has a huge spread, not AOE.
For the record, the Pack Howitzer's AOE as a whole is way higher than a regular mortar. If the spread is larger, then damage distribution is higher too (even if max damage is the same).
Cruzz standardized AOE score says
M1 Pack Howitzer AOE: 39.756
GrW 34 AOE: 17.678
leIG ISG AOE: 16.711
The AOE radius is 20% larger, and all AOE distances are 50% larger. On top of that, the scatter on the Pack Howie is considerably better than any mortar's, so it's even more likely to hit with that larger AOE too.
I would personally agree that the autofire AOE is actually borderline ridiculous.