Seems like you do a pretty good job against place 20.000 in the ladderboards. Saw nowhere in your description what your super army with no AT capabilities will do against several T34s or even T70s.
Playing mostly with one faction and almost never with the other can be deceiving. From place 300 with one faction you comeback and play at place 5000 level. It's normal to win even if this is not your usual army. I was falling in the same trap while playing soviets.
There is some truth in what you say though. And that true is that now, at the current state of the game, the best chance of german player is to cut as long as possible his opponent fuel, or to seize it as long as possible to deny heavy vehicles build or call ins. Tbh these are the only situations in wich I won after the new patch, when I was agressive enough and I succeeded to deny opponent's fuel. In a balanced situation (one fuel at me, one at the adversary, well.... after very long games, the russian oponent won).
About T70... Yep I forgot to mention that. It comes out 30sec-1min before Stug III E = problem solved or just upgrade PGrens with schrecks put them in 250 and chase T70.
T34? the game ends too quickly to bring t34 on, and even if 2x Stug III E + PGrens in sdkfz with schrecks can deal with it.
Assaults and Sdkfz 250 allow me to take control over whole map, cut off fuel so Stug III E and schrekcs are enough for "heavy" units (none IS, ISU, KV will arrive - too few fuel).