Recoil is not designed to make players use burst or tap fire to improve accuracy, only spread is. You still need to control recoil and use burst or tap fire, just like you did in previous titles.
I don't know where you get this idea that specifically assault rifles have "inexplicable random spread". You could argue that assault rifles need to have their spread values adjusted, but they aren't mechanically different from any other gun in the game as far as I can tell. This means that the "double penalty mechanism" as you call it, doesn't exist.
Assault rifles can be used perfectly fine at longer distances in Battlefield 6, unless you're specifically using an assault rifle that wasn't meant to perform well at long range to begin with. The SOR-556 is perfectly capable of killing people at well beyond 100 meters. On the contrary the M433 struggles quite a bit beyond close to medium range.
Suppression in Battlefield 6 isn't ineffective. It does what it was designed to do, which is to stop health regeneration.