I think one of the main reasons why so many igls and some initiator players who get clowned on for not being able to shoot back is because of their movement and the way they peek angles, basically they are easier to kill.
For instance, you see players like boaster, FNS, boostio get insta headshotted when they peek players but its usually them not peeking correctly instead of other player being cracked. Usually their gun barrel or their body's edge sticks out before they fully peek angles or they swing extra wide not expecting to see a player on an off angle.
I think you can see this difference when you watch GC as well, you can only spot 3-4 players in entire server who knows how to peek, but in tier 1 its usually around 1-2 players in the server who doesnt know how to peek.