Very mild take: S3 is a very reliable, relatively cheap, high latency, key-value store.
The reason I don't think about flies on a UNIX-derived systems as a key-value store (filename->file content), is that in such systems, we have many things that aren't really files that expose a file system interface regardless.
The reason I don't think about flies on a UNIX-derived systems as a key-value store (filename->file content), is that in such systems, we have many things that aren't really files that expose a file system interface regardless.