You have the right to disagree, but all that is irrelevant to Pathfinder/Ambulance and no there are very few similarities between USF and Soviets.
And USF have better win-rates than other allied factions both 1vs1 and 3vs3 so they do not seem to struggle.
And once more flexible units allow players to "dictate the fight" easier.
The main point that many make is not that USF struggles in all circumstances, but that the only way for them to not struggle is by choosing airborne.
I think the only commander where we can see such a heavy bias in loadout is Soviet's Guard Motor commander. Axis commanders seem to be generally more diverse, only Jager Armour stands out for OST in 3v3 and 4v4. OKW commanders in loadout are probably the most equally distributed from all factions.
I am not sure if I'd nail down Airborne as the only "fix" for USF, but the commander data is strongly biased for USF in all modes. What is notable though is that the rate of Airborne increases if you switch to the top200 while the win rate stays the similar, indicating that this doctrine might be required to stay competitive.
On that point it would be interesting to know if Airborne is part of the free 4 commanders. If so, this effect would be quite exacerbated. Is there any site/post to look up the initial commanders for all factions?