The reason that RR limits it's ham repeater listing is because in many areas these repeaters ill change more than many people change their clothes. We hams like to tweak, tune, change, and experiment. In general the Skywarn, AREA, and RACES affiliated repeaters will remain fairly constant. As such vital repeaters, the likelihood of getting updated for these systems is greater than other repeaters.
One should note that not all repeaters are even listed in the "sanctioned" repeater listings and are jsut put up by various clubs or individuals. Sometimes they are discovered by just word of mouth.