To round out room reflections. An alternative is wall absorption treatment. Or live with image confusion.
Obviously "your" dealer is more interested in sales than good sound.
Why does pulling out main speakers from wall improve sound?
Ask my dealer this question and he was stumped. He said it's a good idea but couldn't say why. I see speakers pulled out eight or more feet from the wall in very nice systems.
The drivers are facing forward, and when there are no ports in the back of the speaker so why would it matter?