While there's more that has to be learned to do a J2EE scalable app, you can't do it at all until you succeed in putting all the pieces together. It's a PITA, but it does lead to working large applications.

Yet I somehow encounter bad Java apps that don't scale. So the magic J2EE pixie dust doesn't seem to work any better than the magic Perl pixie dust :-)

You seem to be saying that you can give a non-gifted developer (whatever that means) J2EE and they'll have a better chance of producing a good scalable application. That's not been true in my experience.