That's the thing - the choice isn't between languages, but between tools. For example, having a lot of libraries is not strictly a language feature, but it does

That's the thing - the choice isn't between languages, but between tools. For example, having a lot of libraries is not strictly a language feature, but it does effect choosing one over the other. On its own, as a language, PHP doesn't have much going for it. You can clean up PHP and break compatibility, but then you've lost much of its value (and what you'd get wouldn't be better than Ruby or Python anyway). I'd bet most PHP users don't even know PHP, they just install Wordpress or Drupal to run their site and maybe modified some templates etc. As for deployment, it's easier because it's already there. Almost all hosting companies support it. Most (I think) Apache installs have it on (or easily activated) by default. This is the reason other languages don't have anything comparable (in popularity, not in features) to the above CMS.