Annotations are not required to use either of those libraries. Doctrine allows mapping information to be defined in XML or YAML files. For Symfony, the @Template annotation is not part of the core at all: it is part of the SensioFrameworkExtraBundle, which can be turned off easily. The normal way to render a template is:

    return $this->render("MyBundle:Controller:template.html.php", array(...));

That said, it would be easy enough to add the static variable-based mapping information to Doctrine as a metadata driver, and create a version of SensioFrameworkExtraBundle that does the same for its annotations.