Theres a difference between being a rookie and being a complete retard. The accuracy in this game is definatly the latter. Theres a fine line between realism and frustration and this doesn't even acknowledge its existance. Especially when enemies can hit you from 300m with grenades.
The grenade issue is legitimate in Clear Sky but was fixed AFAIK with patches and does not effect the other 2 games. I personally have no issue with the realism in connection with weapons and accuracy. Drop me into the Stalker world and I would be a complete retard when it comes to picking up a gun and trying to survive. I would in time become better with the help of better weapons I find along the way either on bodies or from people willing to sell me better weapons & upgrade & repair them and my accuracy would improve with experience. I feel this is accurately represented in the Stalker world which is not the case in the majority of FPS where you seem to start of as being ex special forces being dropped in a linear maze.