I would assume players' front ends don't have any idea about the "damage level" of nearby objects. More likely, you drop bombs on a hangar, send the host "I just did 1,000lbs of damage to this hangar," and the host returns "You killed it." I believe this is why you see everything smoking when you first enter the arena, even if it's a few seconds from coming up.
That being said, the status of the objects (up/down) would have to be relayed and the server load would be greatly increased by tracking the damage levels and serving the status. That's why destructable terrain is not allowed.