Duplicity as natively installed setup might be restricted by package
management and alike from the host OS side. This usage of a container
based setup will provide more flexability with upstream providers for
Backups.

Concret: One major issue with CentOS 7 was the installation of the b2sdk
without messing up the hosts python installation. Therefore running it
in a container seems like a good solution as all hosts have container
engines installed anyway.