Extending the IoC container?? A ControllerFactory?? You never do anything like that in Symfony. The thing I appreciate most about Symfony2 is how it enforces good design patterns.
There's even less reason for a scripting language with a GIL to be saddled with this level of complexity, than there is for Java.
These days, I'd rather use the basic components (e.g. Symfony's HttpFoundation library) with something like league/container (formerly orno/di) and a simple routing library like nikic/FastRoute.
Oooh do enlighten. I made an argument when Symfony2 first came out that PHP isn't Java, and now I've been brainwashed to think the Symfony community is right.
Very refreshing to here an alternative point of view :)