it is something that happens in games where the weapon has a range greater then the users LOS, for gameplay reasons LOS is restricted..but in order to give some long range weapons the correct feel, they have a range longer then a soldiers sight
IRL people can see quite a bit further then the ranges shown in this game...actually, barring a obstruction or lack of light, we can see all the way to the horizon..beyond a certain distance our vision blurs and things become practically unidentifiable, but they don't just vanish. (in order to assist with long range optical indentification, various optics like scopes and binoculars can be used, turning a dot on a hill into a lighthouse)
now when firing at something far away that isn't identifiable (but has an unobstructed straight line of sight to it) it is definitely still possible to aim your weapon. so I can't say I agree with your reason you should only be able to snap/burst at it