Yes, you should not be able to build whatever you want, as long as the enemy put as much effort in it as you have to put into countering it.
I mean, common... all the german needs to do is place MG42s and he allready forces the russian in a role.
There is not a single unit in russian arsenal that does it the same way.
There should not be that much of a reward out of any unit with that little risk (because the russian has to outplay the german by a lot to counter it). to argument "you can't just build whatever" is just stupid, because then just buff back everything from last patch since Maxims clearly were not broken (you could beat them). Scout cars could be beaten no need for the transported units to die.
they were nerfed because they were not risky enough, same goes for MG42 spam... there is very little risk in it atm.
Also, idc what he won some time ago. Really don't.
MGs are more of a high risk, high reward unit than grenadiers. You can't faust, you can't riflegrenade buildings, and if you retreat too late you risk not only losing a squad, but giving a support weapon to your opponent. If your opponent does go M3s, you are forced to build grenadiers or lose all of your map control. I still don't see the problem.
Your argument against what I said re: "you can't build whatever you want" doesn't make sense. Something being counterable or not is a separate issue from whether or not it's a good thing to be able to force your opponent to react to your unit composition.