Srcset with Optimole?

People write that optimole serves right image sizes automatically without the srcset attribute. Even though I use Optimole and have enabled "scale images & lazy load" using Chrome's developer tool I see that the intrinsic size stays the same for mobile and desktop. If the intrinsic size of the src image is larger than the rendered size the browser is downloading too much, right? If yes and if optimole is not serving right sizes wouldn't it be the best solution to add srcset with optimole URLs?