In 2v2 up it's really common for axis players to build a strong defensive with just a few MGs, paks, and OKW buildings. It's almost impossible for US players to punish this type of play since the only good barrage unit is the priest, which is only in one doctrine. USSR has the katyusha, OKW the stuka, and ostheer the panzerwerfer. Pack howitzers and M8 are both mortar like attrition weapons and aren't able to do that type of offensive damage quick enough to cover the same role as the rocket artillery units.
Yeah I've struggled against this a bit - particularly with a Pak43 up there comes a point in the late mid-game where your pushes no longer gain ground but just bleed your units, but you've no true camp punishing artillery to break the line if you've not gone infantry company.