Hell, that used to be the norm! I remember the TNG movies all had their novelizations out a few weeks prior to their theatrical release. I was about half way through the First Contact novelization when I saw the movie, but thanks to the photo insert in the middle, I knew roughly how the movie would end. I think the reasoning back then was that having the novelization out prior to a movie's release would give a slight boost in sales among those too impatient to wait, although it should also be noted that regulating the release of books has only been a somewhat recent development as often times whenever the book arrived in a store it went straight to the shelf regardless if they were in prior to the official release date or not. It's still like that for the most part, outside of major releases.Which is why I'm always surprised when a novel hits first.
In the past decade or so an effort has been made to withhold the release of novelizations until the day of a movie's theatrical release or the day after. IMO, this sort of thing, combined with the fact that a lot of studios are actually forbidding novelization authors from embellishing on details not provided in the script* have contributed to the fact that novelizations just aren't great sellers anymore.
*Obviously not a restriction placed on Star Wars novelizations, if the Rogue One novelization is anything to go by.