I think it's a deliberate (and, in my opinion, poor) business model similar to mobile app stores: Atlassian has a small army of plugin developers who sell their

I think it's a deliberate (and, in my opinion, poor) business model similar to mobile app stores: Atlassian has a small army of plugin developers who sell their plugins for the platform (and plenty of Markdown related plugins for this purpose, for example), and Atlassian takes a big cut of that (I think something like 20%).