In T192144, configuration was added to allow restricting certain user groups from publishing to main namespace.
English Wikipedia has Abuse Filter rule to try achieving the same effect of restricting publishing to main namespace to users inside "extendedconfirmed" group.
That restriction should be transfered to enwiki config, now that we have structured way of doing these restrictions. Whether abuse filter rule and message override will be removed is not the scope of this ticket, but would be the desired outcome after configuration change.