Well, the use case is multiple people doing things at the same location that add up to more than 1Gbit. For example, think of the connection on a switch with mostly 1Gbit ports but one or two 10Gbit or 25Gbit ports for the uplink. Switches such as this will also have a backplane capable of doing more than 1Gbit.

Individually no one person/port can use more than a gigabit and can't saturate the switch in this case, but combined they could utilize far more.