The biggest issue with replication in PostgreSQL is restoring a failed master, pg_rewind provides the low-level plumbing to do this and it's somewhat integrated into repmgr now - but it's far from being easy to use compared to something like SQL Server Availability Groups. Being the sole Linux sysadmin / PostgreSQL DBA in my organization means I have to take responsibility for this since the tools are complex enough I can't easily throw them over to our Windows admins or SQL Server DBA's in an emergency. This is partially an issue with staffing, but if the tooling was a little easier to understand and robust enough in fully-automatic operation I could just leave common troubleshooting steps in a runbook, but right now when replication breaks it REALLY breaks.