Mary being blest or not has nothing to with sin...Mary being blest had nothing to do with Mary...It was all God's work...
It is so simple, I can't believe you guys don't get it...Or maybe you do but just deny it...
Why did God use a human body for the mother of Jesus when he could have just created a body for Jesus himself??? If Mary had been sinless which rubbed off on Jesus, Jesus couldn't have been the perfect sacrifice...
God can not sin...Jesus had to be capable of sinning...He had to be able to be tempted to sin...He had to get that nature from a human sinner...
Aren't all of us God's work? Was not Hitler, Stalin, Pol Pot, Jeffery Dahmer, etc. God's work?
We, including Mary, were all born with free will. And Mary exercised her free will at the Annuciation.
Finally, do you think God would choose a sinful vessel to become Man for our salvation?