That way, for a restaurant, you would be able to have these modules:
* A card module showing the menu
* A reservation module allowing you to reserve a table
* A billing module that allows you to order the dishes in the card module online
That way, you have 3 modules that you can easily extend or combine with another one without having 1 mammoth of a module that will likely never be used by others because it's so specificly geared to 1 goal.
In this case, you could also change the card module to show for example a list of services you might provide, without having to offer a reservation module or a billing module.
That's the real strength of a good CMS: small modules that interact great with each other, that together build up a great solution :)