Are these things based in actual evidence? As far as I know Maxis hasn't given even the slightest hint that they are going to do a multiplayer world, so how could they have said that you won't be able to build/buy, you won't be able to play with multiple sims, or you will have tasks with deadlines with specific other sims? I can see ways for it to work without these things...
For Build&Buy, it could just act like you are not online when you're changing your own house. Of course you couldn't change community buildings or your own lot while others were on it, but lots of players don't use cheats to change community lots anyway.
For playing with multiple sims I actually just don't see any reason not. Sims autonomously do things in the current game, so why can't they in this game?
For having tasks to complete with other sims, same thing. Why is that necessary?
Yes, the multiplayer option wouldn't be for everyone, but not everyone has to play it. I think it could work really well and be fun. THere are lots of multiplayer life simulaters out there that work and are played by many people.
Not trying to pick a fight, I just don't understand where all this info came from...