The linked post uses CloudFront as an example, which is commonly used simply as a CDN in front of static content on S3. This allows you to take that model and add some dynamic content to it.

I just recently used this model to host a JS widget used on external websites, now I could for example add some basic logic to disallow certain domains (by checking referrer headers) from using the widget.

The blog post says that one of the primary use cases is to help preview content show up correctly on Facebook, etc. So I don't think client-side routing for static apps will work in this case.