Ask HN: Writing and Variables

Microsoft Word makes using variables in documentation a labyrinthine act: over a dozen steps to insert variables into documents, to say nothing about organizing them. For a sci-fi book I'm writing, I developed a text editor that allows me to insert variable names into a document with ease. This allows me to make the character sheet part of the writing process. Here's a demo video of the concept:

https://www.youtube.com/watch?v=u_dFd6UhdV8

Why is applying the DRY principle to documentation not more prevalent?