The Editor in IPS Community is a third-party add-on.  CKEditor, or something if memory serves.

Question is -- can that editor be extended?  Markdown extension to the Editor?  Users are wondering, so I'm asking.

If not, so be it.  Just not something I worry about but they do.

 

You can certainly extend it by creating your own ckeditor plugin or potentially use an existing one that was created. 

A quick Google search found:

https://ckeditor.com/cke4/addon/markdown
Just make sure you use a version compatible with the one IPS uses (4.X not 5.X).