[srcset](https://developer.mozilla.org/en-US/docs/Web/API/HTMLImageElement/srcset)s can have a huge impact on reducing the amount of wasted bytes target sent on over the wire. It can help make sure that different devices get as large an image needed to look great, without forcing them to download a bunch of extra pixels they can't even render. Just like being able to predictably resize images, offering the ability to automatically create a srcset for developers can have a wonderful performance impact for a site.
Testing was an examination of documentation for each service to see if cropping was an available feature. If it did exist, its functionality was confirmed.