This is not necessarily a problem, see for example http://phantomjs.org/
Google also shows javascript-only content in search results now.
Running arbitrary JavaScript on your server will likely cause performance, security and compatibility problems. It's not practical at large scale, and it's not something that would "fix" all the use-cases anyway.
Also, very few companies and no individuals will have the same technical capabilities as Google with it's horde of developers, years of experience in the domain, billions of dollars and ability to control everyone's visitor stream. They shouldn't be the only company that can effectively innovate in this field.
The backend takes the url, gets the HTML source of the website, minifies it, gets rid of the css, javascript, and images, GZIP compresses it, encodes it in Base64, and sends the data as a series of SMS's.
This is yet another interesting idea that will get screwed up in practice because of massive overreliance on JavaScript in modern web development. This is why developers should do progressive enhancement. There are a lot of thing that are possible with declarative markup that are not possible or not safely feasible with imperative code, which generates things on the fly.