Which VMware docs are not confusing :). In other document => https://docs.vmware.com/en/vRealize-Suite/2019/vrealize-suite-backup-and-restore-vsphere-data-protec...
"Offline backups are recommended but not mandatory. vRealize Operations can be successfully restores from online and offline backups."
I'm using online backup's since vROps 6.x and now with latest 8.5 and never experience any issues just stick to the rules from blog.