I find this topic interesting.
The NFL doesn't want gambling to influence their league in any way, and yet they sell their logos to various state lotteries, they encourage pickem leagues and fantasy football, all of which are forms of gambling (they charge for them and have a prize, don't they?)...and more importantly, each team is required to publish their injury list each week. Do you think that's really to help the opponent plan for the game? Of course not, its to help set the betting lines. If a key player is out, they may even give no line on the game.
Anyway, there's a move afoot for many states to allow for sports betting, and that scares the NFL. They feel it will somehow impact the "integrity" of the game.
You can more about the specifics of this in the article below: