Listening to a podcast called "That Was Pretty Scary" with Freddy Pinze Jr and Jon Lee Brody, they talked about how it was actually just a Miramax decision at the time to always put the biggest star on the poster, regardless of screen time. It was a way to sell tickets to the least common denominator. They don't do that anymore and I believe a creepy lawyer sued over one film for like false advertising over it.
The point is, it wasn't a conscious decision like what we saw with Sleuth or Seven or any of those beautiful marketing jobs. It really was just a greed factor. Thankfully, it worked in Scream's favor.