Equestria wasn't always the happy land we know today. Years ago, dark, fiery creatures called the Infernites invaded Equestria, killing everypony in sight and setting entire towns a blaze.
Going into the factor of "Tolerance." This is my first formal rant, I think, so I hope I don't unintentionally offend anyone with this. I don't mean to offend anyone, and this isn't directed at anyone in particular.