Obers are NOT rangers.
Obers are NOT close range assault infantry.
Obers do NOT need to expose themselves to direct fire to do their job.
Why do you assume long range LMG infantry bleeds the same as CQC specialist squad with no mobility skills?
Why do you assume they bleed the same?
Why do you assume 4 man squads should reinforce for similar cost of 5 model squads, when one squad reinforces only up to 3 models and another up to 4?
Why do you assume rangers will not lose models by the time they are at that range?
Why do you assume obers will lose even a single model despite sitting behind green cover as they have zero reason to close in?
You're right, Obers do not deserve the durability they have.
Aren't we are comparing STG Obers with Rangers here? Because you mentioned a lot about STG.
If I want my Obers to sit behind green cover instead of assault, why should I pick STG at the first place? The reason that I pick STG is I want to wipe enemy's team weapons as soon as possible so my other units could advance along with Obers. And Rangers perform much better at wiping team weapons.
Yes, I assume that Obers bleed as much as Rangers during these assaulting scenarios.