What is purpose for docker hub : I can't imagine why do i need docker hub

As i know, we can't push on docker hub with docker-compose 

It is just a hub which contains image only.

We can push our repository to github so that someone who want to execute our source can pull it from github.

Then, they can run command like `docker-compose up`. I think this is all we need with github or bitbucket, not docker hub

Is there something more feature i can use or i have to consider with docker hub?