Actually you're wrong. Tiger Ace was truly unstoppable because it simply wasn't possible to field enough fire power when it hit the field both early and free of cost. Assault grens also were unstoppable for similar reasons. Crying about 'shitposts' in a post that is, in and of itself shit, is kind of ironic. L2P (the P is for Post, in this case).
Assault grens actually were very "stoppable", all you had to do was hit retreat on your engi and put up T1 as soon as you've seen them. Single M3 with flamers hardcountered all of them.
Thou it was harder then now, because soviet tiers still were built for a year and a half.
I'd rather say Osttruppen were unstoppable, because you could easily swarm the map with them and rapidly get to T2 to seal the deal.