Area-fire is an important standard CM tactic, namely if you suspect there are enemy infantry in clumps of trees or buildings etc, saturate them with area-fire to cause casualties, rout them or to start them wriggling and giving away their position.
Below is a screenshot from an actual game, as my Shermans pour HE shells into the woods where German infantry are lurking. (The two German tanks were killed earlier)
Note I've only ordered 4 of my 5 Sherman to area-fire, as I'm leaving one without orders so that he'll be free to pick up his own targets if enemy infantry start running.
Note the craters from previous turns of area-fire.
Also area-fire tends to scatter which can be a good thing because it produces a 'shotgun effect' that blankets a wider area..