Two possible scenarios come to my mind, but both are a bit far fetched. First one being that this is some kind of phishing training & seeing what kind of techniques could be utilized when doing attacks against high-value targets later (or maybe even being a "final test" in some phishing course for some of the more professional groups (those that are run by nation states)).

Another one being that they are doing it to obtain blackmailing material. Maybe they are hoping that there are things in some of the drafts that could be used to blackmail the author (e.g. in some cases there could be things that might be considered to be racist/sexist/similar, but would normally be caught by the editor).