I really can't understand the reasoning behind bethesda lack of early review copies.
It might have gone ok with Doom (SP impressions and word of mouth saved it), but considering we only had impressions of the mp before it launched, I must say that I think it would have sold a lot more and a lot earlier if the greatness that is the campaign would have been exposed by reviewers.
Dishonored 2 is another case where people seem to love it, but even if there was a very strong marketing push in the end it amounted to nothing because the hype just vanished when it launched.
And now we have Prey, a new game, that people seem to like (myself included), but hasn't had the best sales. First of all, no marketing push, and secondly, it is a new type of game, completely different to it's predecessor, so people didn't have a good way to measure it before it released. With Dishonored 2, you already knew that the first one was good, so going in blindly wasn't a huge issue, but as Prey is "new", and made by a new studio, I think people were more eager to wait for reviews, and because they came after it released, hype had already dissipated.
That is my take, I might be mistaken, but I know what I said about both Dishonored 2 and Prey has happened to me (I wasn't very interested in Doom).