I'm only surmising here but, I've often wondered if, had Joe Kennedy not had the stroke which left him almost helpless if he would have stopped his sons relentless campaign against organised crime.?
As has been said he had quite strong ties to the mob and I could be wrong, someone will tell me, but I thought the campaign began seriously after Joes stroke/heart attack?
Maybe by trying to wipe out the mob guys the Kennedy boys were trying to clean up their own history...the other end of the scale where Mike in GF3 tried to clean up his history for Mary and Anthony..in GF3 Mike says something like 'the higher you go the worse it gets' that seems true

FH