Closed-End Exposed Zippers Cannot Be Sewn Into A Seam
While most zippers can only be sewn into a seam, a closed-end exposed zipper is cut into the fabric surface and stitched similar to a slash pocket. Exposed zipper are just as much functional as they are decorative contributing to visual aspect of the garment's design. Regardless of where it is on the garment, in order for the zipper teeth/tape to be visible, the zipper has to be stitched into a slot that molds around it's angular lines and houses it in smooth, flat, tension-free construction.
If you attempt to stitch a closed-end exposed zipper into a seam, this slot is difficult to create. This is due to the bottom stop's square edge around which the fabric should be evenly folded featuring two defined right angles. If you attempt to sew an exposed zipper into a seam, the seam edges can only blend into a V as they transition to the stitched portion of the seam at the bottom.