I am not sure if that procedure covers major versions (13 -> 14 for example), but if it does, they are ahead of the curve. On GCP, you have to backup the database and restore the backup to a new database. On self-hosted installs, you have to pick one of these processes: https://www.postgresql.org/docs/14/upgrading.html
They do an in_place upgrade using pg_upgrade I believe. They do have to regenerate system tables - they also automate I think some updates to system statistics. But for very large databases this really is the way to go I think.
They do suggest a backup before you run this in case there are problems, most folks have periodic backups anyways, but the backup is not used.
