Action Types that we say are Old we mean, are no longer in use by the business because we have decided to make a new form that reflects the business better. We want to keep the previous workflows and actions so we do not lose the data, but dont want people raising those anymore.
We want to hide them as they are still valuable insights from data, but we do not want anyone raising actions with these forms, as we created new ones to replace them, as Action Types are not versioned like Workflows are.