Yeah, I suppose it is, once you've got the edge on a guy, there isn't really much he can do other then sit there and take his kickin for 5 days. He's never gonna free himself and be able to turn the tides like a boss. If he's lucky he's got a nice little stocpile of missiles, materials and cash, so he can score some infra damage and make himself feel a little bit better, but apart from that, nothing else he can do. If he's even luckier he might slightly weaken the other guy by taking out some mil buildings.
Just seems to be a bit of a shit boring ass way to do things for both the attacker and the defender.