While I agree Heavy Cav is omnipotent, it isn't far removed from your average tiger commander for Ostheer, for example. It just has doctrinal elite infantry instead of nondoc.
E8 is signifigantly better at getting a single lucky hit in on a heavier tank than a P4, sure. Is it worth 30 extra fuel and the drop in AI firepower to be marginally less helpless versus a Panther? On the historical 76mm front; the 76MM Sherman has not only (MUCH) better rate of fire but also better AI profile for the individual shells. It's no P4 or M4A3, but it's a long shot better than the M4A3E8, while also having the APCR shell with better penetration and reload time than the M4A3E8, and all of this is without a power creep series of buffs towards it. (The unit is so untouched it retains the borderline absurdly overpowered ROF from its Soviet days, which couples nicely with vet and radio net)
The worst USF commander is Infantry. Rifle Company is actually pretty good now imo, though I agree it is overshadowed by Heavy Cav, in great deal due to the heavy tank buffs.
If this is your definition of hard counter, you may as well say the P4 is a hard counter to the M4A3 or T-34/76.
Victory against a P4 is as much RNG as it would be for the P4 to beat the E8. It is hardly decisive and hardly a "hard counter". This would be more along the lines of Panther vs M4A3, or Panther versus M4A3E8 for that matter.
I'll do a whole 'nother series of tests if this is not convincing to you people. If I can figure out how to record on this machine, even produce video.
IMO Infantry pretty good in teamgames sure it isnt good in 1v1 i agree but its main strength is team games(like many commanders) with the priest.