Spec and features are intertwined. Customers who switch away from AWS S3 still want to use the same SDKs, libraries, etc that support S3 API. They don't want to rewrite their applications to use a new API. So then is it feature coverage or spec coverage?
It's both? Customer doesn't care if spec is 100% covered if feature that they are using in AWS S3 isn't supported.
Also, who is rewriting their application to change interaction with an object storage? People that directly use some S3 sdk all around the app should read a book on software engineering or at least a blog post.
