Also, picking a date for versioning is weird as it doesn't contain any information other than when the Changelog was set in stone. Too bad this decision was made, and Docker choose not to value the stability of SemVer.
Docker is a collection of many different components, exposing many different interfaces. Semver in Docker version doesn't make sense for the same reason it doesn't make sense in Ubuntu or Windows.
$ repoquery -q --provides docker-engine-17.03.0.ce-1.el7.centos docker-engine = 17.03.0.ce-1.el7.centos docker-engine(x86-64) = 17.03.0.ce-1.el7.centos
...compare to, say, python (I've elided a few things for clarity):
$ rpm -q --provides python python = 2.7.5-48.el7 python(abi) = 2.7
If you do something like: Provides: docker(api) = 1.23
... this at least means that folks can depend on/install 'docker(api) > 1.23' or whatever if they actually want to get a specific semantic version.