Because it’s one more thing to keep track of. Docker swarm mode has all of this stuff and includes the load balancing as well. The Raft store is built-in to Docker swarm mode.
It does have a solution for DNS service publishing for anything that is running in a docker service. All services have a DNS entry available based on container name (e.g., you can reach service foo with curl foo) which is accessible to other services on the same docker network.