I'm not talking 2v2 btw because of the presence of a possible OKW ally giving them access to puma which hard counters the m5 and also if both are Ost they can each get 1 pak denying the effectiveness of the M5 which is to attack where there's no pak present.
Of course Ost will lose some level of map control. That's the entire point of a 'shock unit" like the M5, to swing map control to the soviets until Axis armor comes in. Another thing to point out is that Soviets don't have the luxury of your "fact". The fact is Soviets are forced to choose either T1 or T2 so that's either cons+support weapons or penals+snipers+cons, Soviets have to sacrifice either an effective infantry(penals) or support weapons to begin with. No one is going for both T1 and T2 unless they really need to or its already late in the game and is also contrary to the point of a fast M5 since T1 and T2 consts fuel thus it would delay T3 and ultimately the M5 if both were gotten.
Is Ost fighting an uphill battle when it comes to light vehicle? No one quite knows yet since the patch is still a week old and the meta has not yet stabilized, so until the meta has stabilized and majority of the top players think that T3 sov tech timing is broken it is assumed to be fine as is the opinion of the majority at the moment.
It is not the opinion of the majority ( except die hard sov only players ) that the timing of the M5 is fine.