Right become very thick in case of this dia.
Almost perfect profit.
So, for leaving defect at right, black blocks there.
However, it does not mean that black intends to capture white group at lower right.
If black connect it with 1,
black loses this capturing race.
Now, there is defect at A.
white is so slow and dangerous.
Where there is cutting, there must be blood.
Next time, black can block center.
This is the way white avoids blocking.