It seem you got that the other way round, it is not Donnie complaining about the "non doc vision from t70" but Katukov complaining about the doctrinal spotting scopes although Sander93's long response.
he was complaining about how 222 is not as impactful as t70 and how t70 can spot everything, which 222 can do as well.
Your description of m3a1 for some strange reason is flawed:
M3A3 has plenty of DPS on its own for its timing/class
M3A3 can survive an ATG shot so again it has plenty of HP for its timing/class
ofc, my guy. Very good unit vs OST...maybe for a 1 screen army type of guy
Imagine getting m3 vs gren start with 20 range fausts and proceed to waste all your micro on it, just because it is "good on paper". Might as well save the resources for a future backtech into zis gun, so when p4 arrives you won't get caught with your pants down while parading your "all seeing" t70