https://bugs.winehq.org/show_bug.cgi?id=56476
--- Comment #4 from jrlh@outlook.com --- Why?
It's running a HIGHLY valuable windows application on Linux. It says right in the docs that Wine supports Windows Store applications.
In this case it's just a React app in a wrapper with some hooks to the OS, so far more straight forward then the 30 year old Frankenstein that is the old app, and the old app is going away, so this is an excellent opportunity to support one of the major reasons why people stick with Windows. (especially considering that the ONLY support in alternative applications save BlueMail is going away shortly as EWS is being decommissioned and IMAP/SMTP is being removed from all business accounts July 1st.