While the Ironcliff Fortress was also a guild headquarters, the fact that it was a system's stronghold made it fundamentally different as compared to headquarters built by players.
Because the Ironcliff Fortress was a quest reward, it had a complete encampment defense setup. The walls around the Ironcliff Fortress were of the top quality and there was no longer any room for improvement. On the other hand, the normal guild headquarters' defense required players to constantly improve it to be able to reach this level.
Therefore, this stronghold encampment was born to be much stronger than other ordinary encampments. Of course, to compensate for the difference, the ways to guard these two encampments were very different.
For example, ordinary guild headquarters would have the guild's gate and the guild crystal as their two layers of protection. The encampment would only be destroyed when these two layers of defense were broken through.