Almost any "horror" movie would be especially short if any of the characters weren't spectacularly dumb. Obviously, the applies especially to a "horror" television series.
(I'm guessing it's because the writers are lazy.)
Hollywood must be envisioned, in my opinion as that beast favored by film-makers, the Tyrannosaurus Rex.
The Tyrannosaurus Rex was, we are told, huge, equipped with amazing muscles and reflexes, sharp teeth and claws, and a pea-sized brain.
Hollywood is huge, equipped with high-quality special effects crews, advisors of every kind, make-up artists and inventory specialists, decent actors and a logistics system that would put some militaries to shame - controlled by writers and directors with pea-sized brains.