Is it true to say:
A) OUTPUT chain is for the packets that are "generated" by the machine itself i.e. OUTPUT chain affects connect() function.
If yes, why would you want to control these features on a firewall? A firewall is not a web-server which listens to port 80 or a client which connects to that port.
Am I right to assume these chains exist only to address the needs of a multi-purpose machine (which is, say, firewall and web-server at the same time)?