Currently the kcmshell5 executable is in the kde-cli-tools repository and dependson plasma-workspace. To avoid a dependency to that project apps like kwin or kdeconnect have their own kcmshell implementation.
My suggestion would be to move kcmshell under the name kcmshell6 into the kcmutils project and thus avoid having duplicate implementations of the same utility.
This could be done when KF6 is branched, without having to worry about conflicting names.