Is pg_dump a Backup Tool?

Recently, I've been hearing a lot of experienced PostgreSQL users reiterate this line: "pg_dump is not a backup tool." In fact, the documentation has recently been updated to avoid saying that it is a backup tool, to widespread relief. Experienced PostgreSQL users and developers have been publicly called out for having the temerity to assert that pg_dump is, in fact, a backup tool. I find this narrative deeply frustrating, for two reasons.