This is a late reply, but the reason for this is mostly the casual nature of this game and the way the super strong aim assist auto locks on when you ads. If you actually put the crosshair just above a players head, then quickscope in and fire the aim assist will auto lock to there head and they will die. It's a bit jammy, but if you learn to abuse this feature you basically end up with what you describe. In some cases aim assist actually fights against you when playing sniper, such as moving targets. Sometimes I feel like turning it off, but the auto lock aim assist is too good not to abuse.
So for those players that think that guy has amazing aim, know that the aim assist in this game is bs and the game kind of aims for you.
Skill
I'm ok at being a sniper
But not great at close quarters with them
