If I understand correctly, received accuracy affects the chance of getting hit while armour affects the damage taken by making shots "bounce" off.
IIRC, suppression is added if a hit is rolled so received accuracy only serve to make it worse for the MG instead which is why we have units like Ober/Paras/Grens/Rifles/Volks just "ignore" suppression by MG.
What if armour is put in place of received accuracy? The MG would still roll a hit - no damage (reduced damage if the idea in the next paragraph is considered) is done if it fails to penetrate but the suppression should be adding up though. MGs won't be useless against these squads and might work better assuming they don't "outDPS" you.
You might have those situations where soldiers start tanking and take no damage but I think (not sure about this) that can be solved with implementing deflection damage. Also, isn't there an immunity system where you can make certain things immune to certain types of weapons? Tanks are immune to small-arms so the deflection damage maybe (not sure) won't hurt the tank at all and only work against infantry. Thoughts?