If you have ever worked in SharePoint in the last couple of years, one of the most valuable tools is the ability to discard your changes that have been made to a SharePoint page. If you wanted to try to adjust different things in a published page, but decided you didn’t like them or they wouldn’t work, you could choose to discard the change and your page would revert back to the last version that had been published.
Unfortunately, Microsoft has chosen to remove this capability from SharePoint. I wish I could say that a reason was given, but I am hoping that they can receive enough feedback to put it back. If you would like to provide feedback, please vote on it here:
https://feedbackportal.microsoft.com/feedback/idea/ece9d1b4-e668-ef11-a4e7-6045bdb238dc?q=discard+changes
I can only believe this would have been done to accommodate other features such as co-authoring. I believe there are ways to balance both without removing a feature with far more use than co-authoring.