I’m trying to understand. There are plugins for markdown-it that expand its features. If Discourse used Markdown-it as a full dependency, it would be reasonable to wonder whether adding features to that dependency would bring them to Discourse.
But it seems that however Discourse uses markdown-it, it’s in some more limited way that cannot take plugins to expand the feature set.
Strange that the search link that worked before is broken now. Here’s an example direct link: markdown-it footnote plugin. That has instructions for adding footnote capacity to markdown-it, and the hope was that if Discourse uses markdown-it (which was my understanding), then it would inherit whatever capacity the local instance of markdown-it had to offer. But it seems that hope is not going to work out.