mongodb/docs — pull request #1280 by lissom (2013-09-19 15:56:44+00:00)
Title: Update sharded-cluster-config-servers.txt

That statement is not true. People following it has led to system failures due to config server overload(according to stories from SA/CE in training bootcamp). The docs also appear to fail to mention that the config servers hold the distributed locks. A large source of read/writes.