How to create assets with XD

I introduced XD to our designer today... the first and what I would think would be obvious, was; how do one go from the "design" and "prototype" phase, to development. In Photoshop, one can easily create the graphical assets (images) needed to build out a page.

I would expect something to facilitate that flow - whether that be an export of web optimized image, or export of an Artboard to Photoshop (or both).

I'm not finding a word about that obvious "next step" in the development cycle in documentation or intro material.

The bottom line is, the incentive to design in XD is pretty small  if one must redesign an entire layout in mature environment like Photoshop to create those assets.