> I've read before that DMCA takedowns only cause content to become inaccessible publicly but not actually deleted
This is a violation of the takedown request, and can result in harsher penalties for the host. It's not a great example, but MegaUpload was faulted for doing just that: Removing the link between a url and the content that url pointed to. Granted they did deduplication so there could be other links from other urls pointed to the same "illegal" content, which is what the USA went after them for, but the fact remains that it's a pretty clear grey area whether or not the host can retain that data after someone claims rights to have it removed for their own future benefit.