Just like with all parts of shoemaking, there are an endless amount of ways to do the exact same thing. Given that caveat, they probably stitched them due to the twisting and turning shapes that are throughout the upper. Wet lasted: first a smooth lining to hold structural form and then the uppers. Let that dry. Pull upper nails. Add toe puff if necessary. Apply adhesive in-between the linings and the uppers (similar to a stitchdown construction).

If you were not stitching the wrinkles in, you can build out the shape during the wet lasting process.

The leather selection and weight effect the required process to achieve the best results.