For a dress to fit perfectly, especially a strapless gown, it must have boning inserted in the seams.
This gives your dress structure and prevents puckering and drooping.
If your short waisted, it helps the dress from bunching at the waist.
Part of the “support system” comes from boning in the seams. The more boning your gown has, the better the gown will look and fit.
A well made gown will always have boning!
In most cases, boning will prevent you from having to wear a bra or any type of body shaper. It’s already been made in to the dress.
I always put it back in the seams when I alter a dress and if the dress wasn’t made with it, I put it in.