Wtf is an assault tank? wtf are you even talking about. Blame the united states for treating tanks and crews like fodder for this representation. Not like they NEEEED a jumbo anyway. Jumbos would be a cool doctrine, but how you're stating your opinion is pathetic. The USF faction is far from bad. If you don't like how america rides the coattails to freedom in this game, then you are playing them wrong and should probably switch to axis if they are so unbelievably good.
Treating tank crews like fodder? When the Sherman made its combat debut it was one of the best tanks around. They correctly determined that Tiger class tanks would be rare. They incorrectly predicted that Panthers would be similarly rare. When this assumption turned out to be false on contact in France, the Pershing was rushed into service as fast as possible, with the M36 Jackson acting as an interim solution on the TD front. In any case, the most common foes faced by the US tanker were assault gun/tank destroyers, medium tanks like the Panzer IV, and AT gun positions. All of which even the standard 75mm Sherman was a match for. It would be incorrect to say that the US tanker was mere cannon fodder marched suicidally into the superior German Krupp Stahl, and only capable of overcoming them by outnumbering them 5-1!
In Company of Heroes 2, the most common AFV foe that a Sherman faces is a Panther and Tiger. OKW doesn't get mediums except through a useless doctrine, and the Ostheer meta calls for T2 stalling into Tiger callins. It would not be an exaggerating to say that I've faced more Tigers than Panzer IVs over the past six months of multiplayer. And I have faced a tiny number of Stugs, comparatively. The most common reason to see a Panzer IV is because of Tiger Ace cheese, where they are allowed to pump all their fuel into T3 then still call a supertank in at the end.
The question is not so much whether USF is competitively viable. It's extremely viable in 1v1, it's moderately viable in 2v2, and it's still fairly mediocre in big team games. But the issue we're pointing out is that the game is designed in large part to cater to WWII gamer's Panzer fetishes. Germany gets all of its cool toys, even ones that saw limited or no combat. Then when people ask for the Americans to get some of their cool late war toys, they start throwing around arguments about how historically inaccurate it is. This is quite funny in the face of how broadly ridiculous the unit compositions are for armies in CoH in general, to say nothing of how many limited-production vehicles that may not have ever seen any combat get featured as core units of factions.