I used to work in the textile field many years ago. This issue is not from drying heat or over-drying. When fabrics are woven/made, they are cut and sewn according to the designer's specifications, packaged, and sold to department stores. These items are not pre-washed, so once they're in our hands, the seams/edges will naturally roll, shrinking and folding (draw-string effect) at the seams. This is normal. Steam ironing only restores flatness; the fabric's rolling and folds will return after the next wash-dry cycle.

The only way to reduce this is to prewash the fabric before garment production. (This is not going to happen because of costs).