Why have a fake suppressor:
1. For sales display at gun shows. The same weight and feel of the real thing but no risk if stolen.
2. As a perm attached barrel extension to bring the guns barrel length up to 16+ inches. Some will work as a flash suppressor, some will make things louder, none will make things quieter.
3. For show and looks in a display at home.
4. As a movie prop with a prop gun.