We cover why this is not done in the article, namely location transparency (our files aren't always in S3), and partial-failures. A simple client-side uploader

We cover why this is not done in the article, namely location transparency (our files aren't always in S3), and partial-failures. A simple client-side uploader like this doesn't handle cases like the upload failing part way through. For example, the user closing the browser or losing connectivity.