2-3 zone is not broken at all. The problem is that every team that runs it, doesn't have the appropriate personnel. Its ironic though that everyone thinks shot blocking is useless in the game as well, but in fact the two work together to provide a very effective 2-3 zone.
Guards-At the guard positions you are going to need a lot of OD. Reason being, they will be defending the majority of outside shots but not much inside. They will however guard some driving layups, not many, but some so you will want SB to disrupt the layups. The guards arent the problem on most teams since a lot of teams have good OD on their guards anyways.
Forwards- These may be the most crucial in having an effective 2-3. You will need not only good ID, but you will need good OD as well. Reason being they will be defending quite a few jumpshots themselves from the players who attack the 2-3 zone effectively. This is where many teams fail at because they have the good ID but fail to pair the OD with it. Usually SFs can get by on most teams, but many teams dont have that PF that can defend the outside like you will need in a 2-3. Also, you will need good SB on them as well. They will be defending quite a few driving layups themselves so SB will disrupt that and alter the layups leading to less conversion rate.
Center- This is where teams are just flat out unprepared. SB is useful for a reason and not many people believe that. The center position defends the majority of driving layups in the defense so you will need high ID and SB. Reason why many people believe 2-3 doesnt work is the lack of SB