I only play 1v1 and 2v2. I can imagine the game being horrible in 3v3 and 4v4.
Ah, there's the thing, Unshaven...
It *feels* worse in 2 v 2. In bigger games there are variables...
1. Noob teams - you get lots of Axis noobs looking for EZ mode. They don't leverage faction advantage
2. Synergies - support synergies are more powerful in big games, the most obvious being the Ostheer logistics biyatch role, or Sov arty dude
3. Uneven balance of skill - poorer players can be carried by better ones, no hiding place though in 1 v 1 and 2 v 2
4. Maps. The maps in bigger games change the dynamic - you spend half the battle getting back into it.
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However, where you get a fairer match-up, yes balance can deteriorate into the heavy tank-fest. Lots of people love the heavy tank-fest, but until the American armour problem is solved (not necessarily by a heavy, but by tweaking Jacksons so they are more survivable) then the game remains hilariously dominated by OKW.