We have police forces to do the policing in this country, and the NFL is not the employer of the players, so the NFL has no business in this. Players are employed by the individual teams.
I do agree that part of this is on the players for caving in the CBAs, no question. The leagues should be able to monitor PEDs, in order to assure a level playing field among the teams, and it should be able to set up the rules of conduct (play and play related) on the field. Beyond that, if a player wants to smoke a joint, or he breaks the law, that's for the teams to deal with. The players have been fools to give such power to the owners, who already dominate the sport.