I think you mean it's successful because of its lack of rules, and I disagree. WordPress's low barrier to entry stems from a combination of PHP's ubiquity and a positive feedback loop of popularity. More rules wouldn't hurt either of these factors.

More like PHP's ubiquity which leads to easy installs for non-developers. The reason wordpress is so successful doesn't revolve around the devs. It's because your everyday blogger can setup a blog in 20 minutes. The dev focus comes from having so many users.

That's pretty much what I was trying to convey.

Umm, whatever, no rules implies _no safe assumptions can be made_. Getting WP plugins to play nicely with each other can be like sorting out INIT conflicts in the Mac OS 6 days.