Maybe I'm misunderstanding here, or am missing something:
Why the extra step to "send all inputs to one adress" and then split them up again?
As far as I remember, coinjoin does exactly the same thing you suggest, except it creates one huge transaction, where everybody throws inputs at it, defines new, "anonymous" outputs, and signs the whole tx when they are happy with the result. It's either all or nothing, the coins can't be taken in between. Also there is no central point whatsoever. Except, for convenience, a central point to organize all the people and inputs, outputs and the like.
I see a market for such a central point. TOR and anonymity would be fine too, an .onion address would in fact be helpful. I'd throw a small fee at it too.
Ente
Step 2 in my method is supposed to combine all the unspent inputs into one giant input. That mixes all the coins together. Coins in the same address from different inputs are not necessarily mixed yet.
Bitcoin works with inputs, regardless of addresses. One address can have several unspent inputs, and this is going to be the case when many people send to one address.