If it's anything like gaming is these days, you f'ck over a film and the studio / publisher makes it very difficult for you to get exclusives or previews in the future.
A lot of games get that 'safe' seven so as not to upset a publisher or developer and I would imagine film studios use the same methods. There's a lot of money going into these films these days and the studio politics mean that investors need to be kept sweet.
Ergo, the journo and reviewers at the end of the process get used and bribed or punished and black listed.
You can virtually guarantee a studio or publisher without any financial clout will not be handled with kid gloves when it comes to reviews.