[narsil]

We ended up implementing a REST API endpoint for SFTP to provide an easy way for web apps to transfer content without having to speak the FTP protocol: https://kloudless.com/products/file-storage/

I can see this being valuable for apps to get user content into S3 more efficiently from the server-side rather than funneling it through hosted servers. The one caveat is programmatic user management, which I'm sure is possible.