Why Smokey/MIB can't kill Jacob by Rockdolfan

I believe the reason the MIB/smokey on the beach can't kill Jacob is because he must first be provoked by Jacob. The MIB says "do you know how badly I want to kill you?" And the very calm and cool Jacob says "yes". The game,all along, has been to try and provoke Jacob into anger or rage or hate or greed,etc. So then the smoke monster may then kill Jacob on his own. To give examples as to why I believe this to be true. 1) The men who enter the foot to find Jacob gone find Flocke who only wants to talk with them at first but because they are angry thay start shooting at Flocke,who then turns into smokey and kills everyone but the lone man who did not shoot at him.(BEN)
2) When Flocke exits the foot,Richard tells everyone NOT TO SHOOT at Flocke. Why? Because you will unleash the smokey!!

Also, does anyone have a theory for why Windmore can not be killed by Ben? Or why Ben could not kill Locke earlier near the mass grave site but "off island" Ben is able to strangle Locke? Ben said "it was foolish to have tried" to kill Locke,or something to that effect?