Do Nginx modules make use of the full power of Nginx?

Nginx seems to be used as a reverse proxy. So, we would find:

[JAVA + APACHE] {1+} -------> [NGINX]------>world.

But one flaw with this approach is that, if we have only one java+apache and an nginx load balancer, then nginx is only as fast as the apache, not any faster.

When we introduce more of those apache servers one could argue that nginx is beneficial, but I still find that inefficient because you would need a lot of those apache servers for handling high traffic.

Ideally I want to have:

[JAVA or C++ + NGINX] {1+} --------> [NGINX](load balancing)--------->world

I find that very difficult to acheive, because none seem to use nginx as application server.

My question is how would I acheive it and does putting the entire Java or C++ business logic into an nginx module allow nginx to reach its full potential (meaning faster than apache, and load balancing like performance).

Additionally, how does FCGI compare to modules for fast C++ business logic integration directly into nginx without any other server.