AR's and why are they in the game?

Genuine question, when SMG's are more accurate and will drop you quicker regardless if you shoot first. They have zero recoil from what I can tell and drop you inside of a second. Whereas an AR is way more inaccurate, can have wild recoil, and damage seems to drop off the second the bullet travels past 5 meters. so why are they in the game? they are useless, the new AR is hot garbage and doesn't seem to fit any situation, if feels like it was added for the sake of adding a new weapon.