Wrong, all ARs have a base damage of 28. However the distance it keeps the 28 before dropping is different, and of course keep in mind normal ammo vs high power. Normal ammo is fine and balanced on the SFAR, the problem as you show is with High Power (clearly as shown in the image). And dont forget the slow firerate of the SFAR vs the fast of others, that means alot to TTK.
And in my opinion all other ARs should be buffed at long range, not the SFAR nerfed. Coming from a BF veteran like me, in the past weapons used to do a lot more damage at range. Dropping down to 15 and taking 7 shots to kill is ridiculous. Back in BF2 and BF2142 (from 2005 and 2006) an Assault Rifle never dropped below 20dmg. Never. Maxium bullets 5, minimum 3-4. Not 7 like now.
For comparison in 2042 the PP-29 (SMG) currently does more dmg at range (18) than quite a few of the ARs who drop down to 15. Stupid. All ARs should be buffed to minimum 20dmg (5 bullets) and compensate that with slightly more recoil/spread instead. Requires more aim and skill then than the full auto spray n pray nowadays.. :P