Sneak attack needs to have advantage on attack except in these circumstances:
Beginning at 1st level, you know how to strike subtly and exploit a foe’s distraction. Once per turn, you can deal an extra 1d6 damage to one creature you hit with an attack if you have advantage on the attack roll. The attack must use a finesse or a ranged weapon. You don’t need advantage on the attack roll if another enemy of the target is within 5 feet of it, that enemy isn’t incapacitated, and you don’t have disadvantage on the attack roll
I am struggling with understanding the "isn't incapacitated" requirement, because from my point of view it's the best time to strike. An enemy has no chance defending himself while being incapacitated.