Most customers seem to drive this by queries and scheduled reports looking at the status of the article process. I do agree that it would be really useful to be able to create assignments and reminders within knowledge articles. There is an ER raised for this which you've already found:
You can create a collection object on article called something like "article assignment" with a relationship to the user and status plus an action to create an "article assignment" record when in an article then select the user and status. This could then be used to query against.
I also believe that in some instances customers have created a one to many relationship between article and a task object that they aren't using (perhaps Call Task?) and then they can customise the Task process for that object to include the assignments and notifications that they want.