That's pretty cool! But the intended use of watchdog is so you can have multiple pgpool-II instances and failover among them (http://www.pgpool.net/docs/latest/pgpool-en.html#watchdog) rather than failure of Postgres. In the configuration described in that wiki what happens when the DBMS goes down but pgpool-II is fine? The watchdog appears to be monitoring the pgpool-II process, not the postgres/postmaster process.
If you dig deeper into pgpool-II you will find that it does not have failover logic. Its intention is to pool connections and distribute query load among replicas, but it cannot differentiate node failure from network partition and cannot promote a standby to master in the case of failure.
If you dig deeper, I think you would find your statement is no longer accurate:
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