because we all know it can be done and if you dont want multiplayer then dont visit this forum.
Sure, and everybody is entitled to have their own personal facts, too.
Skyrim uses basically the same game engine as Oblivion and Fallout3. People have been trying to mod Oblivion to function as multiplayer since 2006, and nobody has managed to get it working beyond being able to get other players to "appear" as NPCs. Cooperative gameplay doesn't work with this engine because the engine wasn't designed to work that way.
Think about it. Every time you cross a cell boundary, there's a load from disk. There are all kinds of other timing issues, like the pause when you open inventory. Is PlayerA going to have his screen suddenly freeze, while PlayerB steps across the cell boundary, and PlayerC looks into his inventory for a potion?
Then there's the AI. How is the AI behavior on PlayerA's local game going to coordinated with the AI behavior on PlayerB's version, given that a lot of the stuff is semi-randomly generated? Everything would have to be scripted, so that if a Mob was attacking PlayerA on PlayerA's instance of the game, it would also have to be simultaneously attacking PlayerA on PlayerB's instance. The game engine isn't designed to do this.
A multiplayer game has to run on a game engine that is designed to handle shared instances. That means it has to have a way of using a two-way data stream, controlling events at the server level, and then the clients have to act as terminals. In other words, all of the AI, cell loading, combat timing, etc. would have to be handled at the server level.
In order for that to work, the game engine must have separate server/client functions built in. Do any of you guys who "know it can be done" actually know whether this game's engine has that kind of capability? I don't think you do.