P4s are already spammable and actually work consistently against infantry. That's a terrible idea.
Barrage is 60 munitions, which alot early game and quite expensive for something that is easy enough to dodge. There are much better arty options that don't cost nearly as much.
Oh ok, I missed the part where flamers, DPs, at nades, mollys and mines are free. Faust cost is fine for what it brings. The Soviets would happily spend munitions on things like shreks/flamesniperHT/bunkers if they had the equivalent -- which they don't.
1) Panzer 4's are spammable and consistent against infantry, but: the German player must pay for two tier escalations, most likely both T2 and T3 buildings as well(skipping T2 right now is suicide). It has weaker frontal armor, weaker AT and much reduced sight radius. That's fine, the SU-85 is a tank destroyer. However, the SU-85 is significantly cheaper than the PIV, so by your admission, the SU-85 is just as spammable as the PIV. And let me tell you: in pairs, it will kill off infantry quite effectively, from a very safe distance, including pak's.
2)Lets say Barrage is 60 munitions. I've seen decent Soviet players reach the time when SU-85's come out, with an excess of 230 munitions. 60 means nothing to them. In fact, if those 60 munitions neutralize an MG42 or even hit an enemy teller mine, your money was well spent and actually returns a theoretical
profit. That's an ATG getting a profit from killing infantry crews and mines.
3) Soviets don't really need
flamers. They can go that route, yes, but sniper scout cars are fine, too, if you want to dip into the manpower solution.
AT nades are a soft counter, and guards can fill that slot too. Many pro players successfully do not incorporate
molotovs into their strategy: They are pretty predictable and delay your access to vehicles. Vehicles like the T70, T34 and SU-85. All of which have a very good efficiency if they hit the battlefield early. These strategies did not require a single point of munitions spent. All manpower.
Mines are good, but the size and design of the maps also makes them very situational. No guarantee a smart player using a Flamer HT will hit the mine in that chokepoint.
Im not saying Soviets don't need munitions. There's moments where using munitions is more efficient than getting guards, and molotovs may have helped you disoldge those grens from a small building, but the Soviet army does not depend on munitions whatsoever.
I'd like to see a german player neglect fausts against scout cars. Im not even going to detail recon runs, medic bunker upgrades, smoke dischargers, etc.