I'm getting annoyed with IDOCs. Since they tend to happen at the same time every day (when I'm at work), I can never participate. So everyone else gets all the good stuff.
QFT! They get the IDOCs pretty much unchallenged during the week, and when the weekend IDOCs happen, the whole shard is there to fight over them.
Maybe an IDOC house shouldn't fall, though it cannot be refreshed by the owner, it just sits there.
With the IDOC house sitting there without a timer on it... it is left to US to decide its fate. They need to introduce siege weapons that take up control slots, battering rams and catapults to knock the thing down. The building should have hit points, maybe around 200k hit points, so if one person was trying to knock it down, it would take several hours, it should take a group effort, 10 battering rams and catapults should be able to knock it down in 20 to 30 minutes.
While they are at it, make camping a viable skill. GM Campers can set up a siege camp which is secure storage for the siege weapons while logged out ( once logged in, there is no such protection ). The siege weapons also have hit points, they are prone to damage by fire and blunt force, they are made by tinkers with components from blacksmiths and carpenters. The catapults would fire the stones harvested from mining, and those can be infused with blackrock for extra fire damage. The siege weapons can be operated by hired NPC's or the player, with the obvious advantage going to hiring NPC's, freeing you up to defend them while they attack.
The NPC's would be a new type, specially trained for siege weapons and outfitted for more protection, making them harder to kill than regular NPC's.
It would be nice if the owner of the house could defend it with buckets of tar from the rooftops or dig a moat around to prevent battering rams ( which would need to be filled with sand from mining ), but that really would never happen, as the IDOC is an IDOC because they havent logged in in a while.