It is not about opening a text editor. It's about what you would type into that editor. The value provided is in the templates, not in the editor.
I only write readme's maybe once every few months or perhaps once a year, and having a template (interactive like this one, or otherwise) that someone else has thought about is super useful to me.
I actually do create a few README files every month (cos of Microservices), but I still don't understand why someone would use a tool to generate README files.