Really, the fact that you're heavily incentivised to lose squads as OKW is my biggest gripe with the faction at the moment. Rather than just being fairly weak infantry with no particular role: Volks really should get a very concrete role/upgrade path, and Obers really should arrive soon enough that they can actually fill infantry slots, rather than almost mandatorily requiring that you lose a Volk at some point in order to replace them with an Ober. I honestly don't see any reason you shouldn't be able to build Obers after the first truck (at a lower power level, obviously).
Incidentally; If the argument is that it doesn't matter if one CQC squad wins against another, I would have to assume that buffing MP40 Volks so that they walk all over PPSH cons wouldn't be something anyone would have a problem with.
I don't like it either but that's the way it currently is. As Katitof said, a Kubel is probably the best way to skip a Volks into a stall for Obers.
The issue eith those is that their late power level is exactly what OKW needs, which fixes their cost and reinforcement in place. On the other hand you can't fully put their scaling into veterancy so that they can be buildable in the late game.
Earlier Obers must be toned down though, at which point they won't be worth the bleed anymore, especially not compared to STG Volks. Reducing the bleed is impossible because of their strong late game. So where should their place be? Early with too much bleed, or late when appropriate but you can't fit them into the build?
The only way to do it would be to increase the reinforcement cost with the MG upgrade. Or they need tp sacrifice their elite status, which would be bad for the faction as well