What makes rpm-ostree special?

[idavydoff]

Hey! I am just diving into the Fedora projects and can't understand some things about rpm-ostree.

rpm-ostree documentation says:

One major feature rpm-ostree has over traditional package management is atomic upgrade/rollback. It supports a model where an OS vendor (such as CentOS or Fedora) can provide pre-assembled “base OS images”, and client systems can replicate those, and possibly layer on additional packages.

But is this really why I should use rpm-ostree? For this I could only use ostree.

Rpm-ostree is ostree combined with dnf package manager but what stops me from using ostree with manually installed dnf or any other package manager to install apps?

I really don't get it. Main rpm-ostree features looks like they are just inherited from ostree.