According to the QnA (part 1  and part 2 ), EM Rifles and Disc launchers are powerful Legendary Weapons but not almighty. In the future, these Weapons will be rebalanced just like some other content - we will continue to revisit the changes and make adjustments, perfecting the balance. 

Wow all the weapons are reworked now and EM Rifle is still indisputably OP.

I'm glad plarium had a solid plan for the balance of weapons and bots from the beginning. They must have hired a bunch of former war robots developers.

6 of them.