"just use postgres from your distro" is *wildly* underselling the amount of work that it takes to go from apt install postgres to having a production ready setup (backups, replica, pooling, etc). Granted, if it's a tiny database just pg-dumping might be enough, but for many that isn't going to be enough.
it's easy to through names out like this (pgbackrest is also useful...) but getting them setup properly in a production environment is not at all straightforward, which I think is the point.