Nextcloud asked in a poll at https://mastodon.social/@nextcloud@mastodon.xyz/115095096413238457 what database its users are running. Interestingly one fifth replied they don’t know. Should people know better where their data is stored, or is it a good thing everything is running so smoothly people don’t need to know what their software stack is built upon?
90% is a bit low if the requirement is a full backup of nextcloud with database that is easily restorable.
If they do backups, most just copy the important stuff manually to an external hard drive.