Why do companies use JFrog Artifactory or other repositories instead of Maven central repository?
Saved bandwith and faster downloads: Artifactory stores the artifacts that are downloaded from maven central. So if another developer needs the same dependencies they don't need to be downloaded again from maven central but instead they can be delivered from the local artifactory instance.
This makes downloading faster because company networks are usualy faster then the internet connection and it also saves bandwith.
As example imagine that a developer adds a new dependency to a project. This dependency then needs to be downloaded into the local maven cache of every other developer that is working on the same project.
On large projects with a lot of developers this means that the dependency might be downloaded 30 times.
Stable builds: Dependencys might be removed from maven central. If you have them in your local artifactory instance the project who depends on it can still be build.
Easier maintenance: Another benefit that has nothing to do with maven: Artifactory provides several types of repositories like for Docker or Vagrant.
So instead of setting up a maven artifacts repository, a docker registry and some kind of vagrant store you could create three repositories in artifactory.
Thus you only need to maintain one application (artifactory) instead of three separate applications.

Some or all of these benefits might also apply to other binary repository managers but as I only know artifactory I can't say something about that.