Right, but now go from 11->12, which is the equivalent of the upgrade path I was describing for MySQL. I either need to install both versions and use pg_upgrade

Right, but now go from 11->12, which is the equivalent of the upgrade path I was describing for MySQL. I either need to install both versions and use pg_upgrade to convert the binary files, then remove 11 (and extensions may break this flow) or do pg_dump/restore. Minor versions on both Postgres and MySQL are painless, just install and restart the server. Major upgrades on MySQL are significantly less painful.