On the ResourceManager's scheduler web page, the bottom of the page shows the apps block. When the cluster has run a lot of applications (e.g.: 10,000+) loading the apps table can take a long time, and that prolongs the plotting of the queue status which is the most interesting portion of the page.
If the user is bothering to go to the scheduler page, they're probably not interested in apps that are not affecting what the scheduler is doing (e.g.: FINISHED, FAILED, KILLED, etc.). Having the RM filter the apps for this page should significantly reduce the time it takes to load this page on the client, and it also helps reduce the amount of apps the user has to sift through when looking for the apps that are affecting what the scheduler is doing.