I wouldn't expect any kind of multiplayer in any of the Elder Scrolls/Fallout games from Bethesda.

It's a combination of both won't and can't. They know how much their games being highly moddable benefits them, it's the number one sales point and virtually the only thing that keeps their sales going for so long.

With a game that can be so modded multiplayer can become impossible. Mmissing, conflicting, altered, new: land masses, NPCs, monsters, items, abilities, this list would go on for a very long time and goes far beyond textures and meshes etc.

The only way multiplayer would be possible in such a game is if both/all playing had virtually the exact same game, including all installed mods and even those mod's settings in many cases. Very few would not guarantee severe to utterly game breaking/crashing problems.

They haven't avoided multiplayer to focus on singleplayer, or to manage resources or anything else, it's because of mods and the heaps of sales/money mods in turn bring both at release and especially in time.