As they explained, they needed a text editor that works in a command line (for Windows Core server installs), works across SSH (because for a while now Windows included an SSH Server so you can completely manage it through SSH), and can be used by non-vi-experienced Windows administrators (i.e. a modeless editor).
Telling people to use nano would of course have been next to impossible. Much easier to rewrite a DOS-era editor in Rust, naturally.