We cannot find out the history of edits at a place. For example:
1) Who deleted a bunch of roads and places? deletion leaves absolutely no trace.
2) Something (like a turn arrow) has been wrong for a while. For how long? Who messed up the turn arrow? How many editors have touched that segment since, and not noticed the bad turn arrow?

This kind of information would help us to learn and improve as a community.
And it could rescue from the trash hours of work that a frustrated new editor can erase within moments.