Looks like you a not top tier player, mate. No offence here. But the main problem with beating german is sum of good HMG42 - volks build into fast Shtuka - PzWerfers.
I do think both of you are right.
In the very early game the strong OKW start with Spios into Volksgrens without having to build or tech for anything is very good for taking the strategical positions like fuel on the middle line of the map first. HMG42 and Bunkers in some decent positions can secure and lock it down afterwards. Most of this 3vs3 and 4vs4 maps are too narrow so there is no room to flank (-> map problem). When you go for allied mortars and the like to counter it the first stukka comes incredibly fast because of resource inflation in the bigger game modes (-> resource inflation problem). And there you have a problem in the big game modes because any real allied counter versus axis faction digging in is CP locked in a commander while ressources float so high that you reach T4 long before you get Valentine/Priest/Land matress and so on (-> CPs not inflated). The only exception to this is the Katyusha so we never play that arranged team 4vs4 without at least one Soviet.
When the game goes to longterm voltadark is right. Because many allied units are bound to commanders, they are more limited in unit diversity. For example USF can only have heavy tank or rocket artillery or long range artillery piece or specialised AI-Tank (Bulldozer). At the same time you need recon planes, elite infantry and offmap which you only get partly with that four choices. Because of this you have communicate with your mates and thats a lot easier in voice chat of an arranged team like voltadark stated.
Axis factions have less blind spots in their unit roster and its easier to cover them with one or two of the more diverse commanders.
Two things that are absolute bs vor 3vs3 and 4vs4 (in addition to ressource inflation and map layout):
1. Infrared HT -> You changed the Valentine and thats fine but this no-brainer has to be changed too, make it a timed munition depend ability at least -> UK Boyz AT recon ability and command vehicle recon was changed too in a similar way and Boyz AT were way less of a problem
2. Ressource abilities -> Ressource drops (Ostheer+Soviet) and Ressource trucks (only axis). I always wondered why axis has more of it and USF has none at all, but although beeing historical ironic thats not the point. It just adds to the already existing ressource inflation problem and shouldn't have a place in the bigger game modes.