Carrear multi-player

I would really like to know why EA doesn’t provide a way to play Career Mode online. That way, I could meet up with my friends, each managing a team, and we could play Career Mode together with more competitiveness. We could negotiate players, switch teams depending on performance, and enjoy all the features of the current Career Mode but with more players involved—just like you can do in FM. What’s the difficulty in adding a mode like this, or is it simply a complexity that EA isn’t interested in tackling right now?