SMG/Assault Rifle Balance

The balance may still need work, but Battlefield isn't trying to be realistic. You shouldn't expect things to be balanced like that. In real life, SMG's that shoot 9mm bullets aren't even used anymore because they can't effectively penetrate body armor. There are many more examples where it would be highly impractical to balance things around realism.

Having said that, it's reasonable to expect that an assault rifle on average has a longer effective range than an SMG does. Just like you'd expect a sniper rifle to have longer effective range than an assault rifle. Those are just broad weapon categories though. When looking at individual weapons, Battlefield has traditionally had weapons that don't really fit their weapon category. Such as an LMG that act like assault rifle, or an assault rifle that acts like a DMR.

SMGs are definitely overtuned in a few ways right now.

1. They have absurdly low bloom at high ranges. Makes no sense.
2. They deal way, way, way too much damage. More than some ARs and LMGs. It's insane.
3. Their dropoff damage while severe doesn't matter because they're too accurate. It's the difference between unloading a clip or half a clip into someone's face.

They basically out shine every other weapon in general except for range finder snipers or snipers in their sweet spot zone.