Why doesn the Sabbat just come down from Philadelphia and kill everyone?
First of all, the battle with New York has taken most of their attention. Secondly, in order to reach Delaware, the Sabbat forces would have to cross through an intensely populated Garou country. Occasionally a war party does make it through. But the nearest safe haven is Wilmington and most Camarilla Kindred kill them on site. That is not to say that Sabbat raids are nonexistent, its just that most of the time it’s not worth it.