there's a couple hundred million people in Southeast Asia. There can be more than one.

In fact, there are. If you look at ports by tonnage, Port Klang in Malaysia is bigger than Rotterdam, and Tanjung Priok in Indonesia is bigger than New York.

What I mean by "transport hub" is a place where you drop of containers to be picked up by other ships to go to their final destination.

So you can fill up a ship in LA with containers going to 10 different Asian ports, and drop them all off in Singapore.

This works best if everyone does that at one central location.

You're right other Asian ports are very big, but I think they more serve as origin or destination.