If we want balance at all levels we need to think about how the team games also play out, partially because many players are in each format.
Your comment has been partially dissected before so I won't labor over it, but the increased micro, the inability to chase, the high pop cost and MP investment, the inability to so much as scare an infantry unit, and the very likely outcome of at least one lost Jackson for nothing are all present.
I would also like to point out that while the 57mm does a decent job in smaller games as indirect fire grows in larger games it becomes completely useless. It gets wiped so fast it cannot keep vet, and it is a MP sink. Late game it struggles to penetrate and gain vet. No other AT gun suffers from this. [side note] Why is focus forward not passive as soon as you hit vet 1? Don't you always want it on? Therefore, the USF has to rely on doc AT tanks to maintain presence, and their options are simple, Jackson or nothing. The Jackson does not give them enough AT to provide critical map presence in the late game.
Another problem, against the super heavies it is no more than vet for those units, and this means that USF without Calliope can do nothing in a team game but rely upon its Allies to break through and then try to widen the gap. If there is no breakthrough its tanks sit completely impotent on the side line, and this leads to unsupported infantry, which leads to more map loss, etc.
Just to elaborate on the 57mm AT gun. Another thread has mentioned it has 1.25 instead of 1 size? Increasing received accuracy and that's why super low rate of surivivability hahaha