Confluence used to have it. Or a similar syntax at least. They went WYSIWYG around 2010 or so. It was a dark day; I still remember the plaintive cries echoing from engineer cubes (we had whole cubes back then!).
The new Confluence they are rolling out is pretty good at converting Markdown to WYSIWYG on the fly. Not without glitches, of course, but I'm thoroughly impressed.