How much of this might be an effect of the recent improvement to the accuracy of indirect fire weapons? There was a time when the 120mm mortar was considered a waste because it almost never hit anything; these days, all indirect weapons have pretty good odds of hitting a stationary target. With the availability of pack howitzer, mortar pits etc, there is a good deal more indirect fire around, and all of it more accurate, and it could be that the inherent vulnerability of the 4-man squad has been exposed as a consequence.
Well, surprise! Which factions' infantry needs to stay still more often in battles may I ask? Soviet's? Nope, because cons need to get close to be efficient. Penals need to be middle distance to have good effect and shocks need to be in hug distance (I never saw a shock squad standing still). USF's? Wrong again, because riflemen are better used while strafing witht heir bars. Not talking about other units that have smgs.... UKF's? Maybe just the infantry section partially, the other units no way.
But...
OKW has volks. If you don't keep them still and in green cover you might not build them at all. JLI's quite the same. Sturmpios (as most axis' units that carry stgs - that are assault rifles not smgs - need to be middle distance while standing still because they have bad moving accuracy). Falls and obers are situational but obers are also better used while standing still if they don't have the stg upgrade (and even with that upgrade).
Ostheer has grenadiers. They are also for standing still and in green cover most of the time, especialy when you upgrade them, because, unlike ppshs which is a close distance weapon and it can be operated while moving, the lmg42 does not shoot if the squad doesn't stand still. Ostruppen... they need to hug cover to survive, let alone kill something. Unupgraded pzgrens are used in the same manner as sturmpios above.
The only squad that can and must be used in an "allied" manner is the AG squad because they have smgs and good moving accuracy.
So may I ask you, what factions are disadvantaged by the fact that balistic weapons have better accuracy these days?