>Having a limit of 5 million files is perfectly reasonable

For ordinary users, this would pretty much equate to an unlimited account. Much like ATT's old unlimited bandwidth accounts. It's not until power users start hitting these ceilings to realize unlimited doesn't mean what they think it means. I don't know if Googs every used that kind of phrasing or not, but you can see where some dev never thought that limit would be achievable so there's no reason to really mention it.