Fridge Brilliance: The Mind (AKA, the Incubators) is a/are being(s) entirely devoid of emotion and totally dedicated to its/their logical goal of surviving so of course the freaking Cybermen, a species dedicated to survival at all costs (in the classic series, at least), would ally themselves with them.
The People, an intergalactic Dystopia based on Nineteen Eighty-Four are allied with The Mind, who wish to extend the life of the universe. Think about it.
Word of God has it that The Coalition holds a meeting every six hours. This means that something aproximate to the figures they give happen every six hours. So, every six hours, The People "Liberate" five species, The Cybermen convert 48 planets, and The Mind spread their cultural meddling to 40. Think about just how huge these factions have to be to give those figures every six freaking hours.