As stated, it's not natively integrated. You need 3rd-party tools to ensure replication is setup correctly, to monitor the connection status and replication lag, monitor schema changes or anything else that might need a reset, monitor the master, initiate the failover, recover or reset the state after the failover happens, handle changes for WAL archival and backups, and handle any network changes to point back to the master/replica correctly for clients.
None of that is automatic and every step introduces problems compounded by the amount of tools used to handle each step. Because of this, the setup is intensive and usually custom to every environment. This is hard to test and be confident in and the source of much downtime or data loss.
Meanwhile CRDB handles all of this seamlessly. As long as you have a quorum of healthy nodes, your database is alive and working. Point a load balancer at all of the nodes and you will always have a database to contact with no other overhead. Postgres could get there, but it isn't anywhere there today.
