80 meters isn't long range.
I'm not saying 80 meters is long range. I'm saying it's medium-to-long range. It's an intermediate category in between medium range and long range. I'm approximating these values based on the accuracy and average damage drop off of a weapon category, combined with the overlap between weapon categories. It's not about the exact numbers though. The point I was trying to make, is that you falsely presented close-range and long-range as a dichotomy, while it's clearly a much wider spectrum.
it just makes them usable to some degree as opposed to completely useless,
You have a really odd idea of what it means for a weapon to be useless. Are all weapons that can't shoot at snipers from a long distance useless? What exactly is the issue if you just get closer to your enemy?
essentially completely removes long-range firefights from the game except for snipers and DMRs
Indeed, that's exactly my point. Assault rifles shouldn't compete in long range fights. The hierarchy should be roughly like this: Shotgun > SMG > Carbine > Assault Rifle > LMG > DMR > Sniper rifle.
There's nothing wrong with an assault rifle that's specifically balanced to be more effective at longer ranges than its counterparts, but on average assault rifles shouldn't be effective at those ranges. Similarly there may also be relatively accurate LMGs that should be able to tap fire at those ranges, especially when using a bipod. Similarly, there may be attachment choices, that also allow for that flexibility.
At the end of the day it's about making the player choose their advantages and disadvantages. You can't and shouldn't have it all.
In real life assault rifles have an effective range of at least 300 meters.
Real life is not relevant here. It's a game and Battlefield has never tried to be realistic. If this were real life, you'd get properly shredded by buckshot at 50 meters, possibly even vastly exceeding that range.