
Originally Posted by
Hitei
Silvermoon isn't well guarded post-Scourge, it's just a city.
It can't "continuously receive support from all the EK". Where is it getting support from? Non-existent Undercity? Gilneas that is busy rebuilding and has to send forces up through a forest region, across Tirisfal, through a pass into the Plaguelands, the entire way through the plaguelands, through the pass into Quel'thalas, all the way up through the Ghostlands and then through Eversong and then has to somehow make it past the Void forces to actually reach the city? Ironforge that has to do all of that AND send forces through a convoluted series of mountain passes and valleys, across a wetlands, through Arathi Highlands and Hillsbrad just to reach where Gilneas is? Stormwind that has to send forces via tram to Ironforge and copy IF's route?
In your scenario, ignoring how the factions in game actually operate, where we're marching resources and reinforcements on foot to help, SMC isn't much better off than Quel'danas is.
Reinforcements from Kalimdor, Northrend, KT, Bel'ameth, etc. would all just sail over to Quel'thalas, and they stop just as easily at Quel'danas as Silvermoon. Airships from Stormwind stop just as easily at Quel'danas as Silvermoon. Armies being teleported in get portaled just as easily to Quel'danas as Silvermoon. If Quel'danas is a nightmare to reach, reaching Silvermoon is not going to be any easier. It is the exact same situation, only instead of being open ocean, it's land where Void forces can sit and shoot at you and land meteor pods the shoot out void monsters en masse.
So the actual difference is that Silvermoon has... walls, and Quel'danas has the Sunwell.
There is a reason that Suramar managed to survive the Sundering and WotA unscathed while Zin-Azshari and much of the continent got destroyed. It's the same reason that Dalaran would be easier to defend than say, Stormwind. It's the same reason that Tazavesh still exists even when the planet spent years under void siege and even when the entire rest of K'aresh was shredded to bits and pieces.
You can't defend a large wide area well, especially against an enemy raining out of the sky. It is very, very easy to defend some small fortified location, especially when that location is one of the most powerful, endless sources of magic on the planet.