@Scorpyon , honestly, it isnt that odd a concept. Get two things (tyres, boxes, whatevers) and put them 3 meters apart. Now try and throw a beanbag from 15* meters away, to land exactly 1.5m from each. Bravo if you can with anything like regularity.
Now try and throw that bean bag at one of those targets and get it within 0.5m of that target. I bet you will more often. I'd even go so far as to say you are likely to manage that two thirds more often.
That is the difference between targeting a very very specific point on the ground, and targeting a person. Note you do not need to hit the button on the person, you need to land it within 0.5m of that person (the base size), for them to be hit. Now if you put that item (somewhere) behind a barricade, so you could only see a little bit of it, and then had to 'lob' that grenade over the barricade and get it within 0.5m of the item, I'd hazard a guess you will do it with 'roughly' the same accuracy as you could the initial spot on the ground that is exactly 1.5m between the two targets.
That is your narrative 'justification'.
*I've picked 15m. If you are athletically minded with good hand-eye coordination and find that too easy on both, go for 30 meters and repeat.