What if an app depends on some information that is only available on the client to do the rendering? Like checking the window width and height instead of using media queries (this is what you do with elm-ui for example), devicePixelRatio to decide which size to use for images, etc. As far as I know, there is no way you can get this info on the server, so SSR might not be possible depending on how you write your code – which means (correct me if I’m wrong) that it’s not possible to implement a generic solution that would work for every case (and this problem is not specific to Elm).