I don't know the details, but the pattern for dead orders is the same: The OM and AC both quit playing (apparently GenghisChris sent a message to some people saying he'd be gone for a few days, but then never came back; I don't know about the others). The order can no longer change leadership, make new alliances, accept new members, declare battles, or spend gold.
Eventually, everyone still active in the order figures this out and leaves, so the order is left with nothing but defunct members. (I suppose a member could convince the admins to delete or just kick out the OM and AC so they could revitalize the order. But I haven't heard of that happening.)
I thought about suggesting that the admins delete these orders, but they provide a nice way for the more pathetic Christian orders to get an easy victory and an ever-dwindling haul (I think the last order that attacked 2VEG got 200-something?), and it's always entertaining when someone actually loses to them.
And who knows, maybe one day Dark Magician Girl will come back from the void to wreak her revenge against the grave-robbers of 2VEG.