The note has something like [categories] in the front matter, and the .md file output makes it \[categories\]
I could use the .md files on disk from the notetaking apps that create them, but having to move and rename the files are extra steps that I'd rather the software do for me.
Best case scenario is the way Iotas does it: It's easy to set a note name, and I make it the file name I want (minus the .md, which the export process adds). Then I export it, it gets the note name as the file name, and I can pick the folder where I want it to go. The app remembers that location, and it offers to do the next export to the same place. I don't have to type a file name or search for the destination folder.
My whole aim here is to remove friction in writing and posting. One of the keys to social media's success is that you type into a single box, hit enter, and it's live. I want to get as close to that as possible with blog posts: One window, as minimal metadata as possible and an easy workflow from writing to publishing with as few extra steps as possible.
Others have suggested that I do this in a text editor, and that's how I've done it before now. I'm sure I could script away most of my issues and do this in Vim. But once I found out what notetaking apps were all about, I thought that it was something worth exploring.