Why Postgres should be doing this? Not every client creates a lot of connections and spinning up PgBouncer is easy. On the other hand, debugging async multithreaded complex code is hard.

Postres project also once lacked replication, calling it unnecessary to the core effort. Now it has two means of replication in core and I'd argue is better for it, especially after suffering through both Pgpool and Slony.

I hope they do develop a native, threaded pooling, even if it were incompatible with some libraries or extensions.