What functionality is missing? What is unsatisfying with the current situation?

  The "preview" functionality doesn't show an accurate picture of what the article will look like, so I tend to save and refresh the live page. However, there is no option to click a button to revert back to a previous iteration of the document if you decide the changes were all bad. There is also the issue of having multiple open tabs which auto-save and may inadvertently erase more recent updates.    

How does this feature request address the current situation?

If we had a version history, even if it was limited to a small number of versions, we could easily switch back to the last iteration if our new edits didn't pan out.  

What are other uses for this feature request?

This will also help fix the "open tab" issue - if you're closing tabs and notice that an forgotten editing tab just auto saved over a newer version of the article, you could quickly go in and swap it for the prior version and restore your content.