Not that I particularly doubt you, but can you show me the math behind that?
Well, I don't have the math, but from my observations over the course of the game's life and my familiarity with the USF early game, the game favours weapons with higher damage models to quickly burst down other models/vehicles unless your name is Conscript Mosins which is neither accurate enough or fires fast enough to compensate for bad rolls. Dead units and models don't contribute to DPS so even if the Garand has the ability to quickly rack up damage when given time, whether you will have those models in actuality is something else entirely given a volley from a Volks squad can deal anywhere from 12 to 60 while a full volley from an M1 Garand deals 8 to 40 and in a game of fluid movement, whether you have time to actually get that many number of shots off is another question depending on the situation.
The DPS between the two rifles aren't incredibly different on paper, but the Kar98k's ability to deal significantly more damage in a shorter span of time allows it kill off the models that quickly expose themselves out of cover for those short periods. Higher accuracy might be a placebo effect on me, but I find Volks generally do better vs units in cover.
Volks Kar 98k Accuracy
Mid accuracy isn't the greatest difference when you have things like cooldown, ROF, etc which allows Rifles to somewhat compensate for their range profile. When you look at where both rifles reach their mid range, you need to be closer with Rifles to reach that 66% at 16m vs the Volks 71% at 25m.
TLDR: Burst damage is generally far better to have those sudden spikes, particularly during infantry combat where your DPS drops as models get lost unless it's late game and both sides have upgrades. You want to drop those models ASAP to kill off the other side's DPS rather than chipping their health steadily overtime. Higher damage and accuracy rifles do the sniping models thing better than the M1 Garand.
Volksgrenadiers will likely have their weapon slots looked. Of course more commander stuff is also on the way, and hopefully, that big adjustment to friendly-fire AOE which is all over the place.