Is this a Bungie thing?It is reviewers thing.
They played only 20-30 hours until the release... after they need more time with big population and finally the Raid is unlocked on Sep 13rd.
No reviewer wants to review a game that they didn't have full experience.
There is a review that give a 4/5 score for it 20 hours and called pre review... he will give another score after 13rd.