build job does not produce recommended rpm-ostree commits
Since the build job creates plain ostree commits which are used from that point on metadata from rpm-ostree and thus certain of it's features are lost.
Historically this was done to provide custom metadata, like certain factory condition labels, etc. Nowadays rpm-ostree supports the specification of additional metadata.
Using rpm-ostree commits will allow adopter projects to make use of rpm-ostree features like automatic creation / management of release version tags.