is there a way to present summary of the last backup jobs across the all DBs at the main OEM 12c dashboard, Enterprise > Summary? I believe it is a vital info which every DBA wants to check every day. Out of box, EM12c configured so that DBA has to log into each DB to see the backup reports.
Agree. But Summary screen is restricted to create that kind of dashboard. You have following options
1. Enterprise -> Summary -> Jobs (You can see all jobs status there, including Backups)
2. Targets -> Database -> Jobs Activities (You can see all Database Jobs there, including backups)
3. Job Alerts -> You can set alert to notify you once backup finish
4. Report -> You have run report to get status of all backup jobs