As far as I know the Reverted edits by xxx to last version by yyy edit summary is the default one provided by Undo or Rollback or one of the other similar streamlined reversion tools As far as I know there is no requirement that users tweak the default message and I believe that s especially true when one is mopping up after vandalism in a hurry I know that when I use these tools I don t always take time to tweak the default message I know that when I see these default messages in edit histories I tend to assume they re vandalism reversion It s fine to wish that people routinely did more in terms of edit summaries on reversions but I think policy and common practice are currently against you