Display work runs on different rules to permanent signage. It is usually needed sooner, it often changes at the last minute, and it has to survive a week or a season rather than a decade. Printing it ourselves means a late artwork change is a reprint rather than a renegotiation with a trade supplier.
Because the same studio designs the brand and prints the display, the stand, the banner and the brochure actually match. That sounds obvious and it is the most common thing that goes wrong when the pieces are bought separately.