Logic with duplication of contacts

Ok, as best I can remember in windows, you maintained your windows contacts in part to be used in windows mail, correct? In XP, you maintained the address book for each user, in part at least, for outlook express.

Ok, so why is there a created duplication now that once you import contacts to windows live, if you want to keep those insync with the windows contacts, you have to do the same FILE MAINTENANCE in two different locations? Am I missing something?

I've looked all over the internet trying to answer this very question in my mind about what I perceive to be unnessary duplicate effort.