Lindelof also gets a lot of shit, but Spaihts wrote the script as well. And everything was approved and guided by Scott, he's not the type to not be involved in the process and give them the main plot points to hit.
I think everyone involved is to blame, and no one comes out well apart from those in the cast who did well with what rubbish they were given, and everyone involved in the aesthetic and look of the world that was created.
Prometheus is an ill-conceived vanity project shoehorned into the Alien universe, that neither stands on its own merits nor adds anything to the film it is trying to complement.