As I said, you misunderstand the teaching...and you go too far in your point.  You're ignorant of what St Paul says too.  

Our "Yes" in fact IS adding something to what Jesus does.

Jesus gives us the dignity of making our "yes" count for something.

Read what St Paul says in Colossians: 1:24 "Now I rejoice in what I am suffering for you, and I fill up in my flesh what is still lacking in regard to Christ's afflictions, for the sake of his body, which is the church."

Was St Paul wrong, or doesn't he make a great point about what is lacking....our yes...our cooperation...just like Mary's Yes.