So once you've mastered php, you move onto something more powerful.

You can do tons in javascript these days also.

Right, but many beginning programmers don't want to start with something boring and move on to the fun stuff. You can't show a CGI form to your friends and have them drool over how cool it is. Instant gratification is key.

It almost has to be at the level of myspace -- look, I can quickly add this picture, or this music, or this text to a page all my friends can see.