This is an interesting approach and I like it! If this functionality were made available we would certainly use it in my community. The [toc] short code is one of the few things I miss from drupal.
I am in the process of moving our operating procedures into wikis in discourse and it’s working quite well. The workaround to no automatic table of contents is to use the details markdown, which lets me tidily display a series of steps and lots of structured information without making the post so long it takes loads of scrolling to get to what you need. I also put some stuff in the second and third post in a topic to separate it for easy access.
(Maybe this topic needs a more detailed title to distinguish it from the other one, or they can be merged?)