The Fifth Patriarch said:

The cycle of birth and death is a matter of utmost urgency to existing human beings.

Yet day and night you seek merely blessings for your good deeds, and make no effort to free yourselves from the bitter sea of birth and death.

Should your real nature be obscured, the merits of your good deeds will not be able to save you from the endless cycle.

(The Platform Sutra)

The Sixth Patriarch explained blessings as follows:

Those deluded cultivate blessings but not the Way, and assert that nourishing blessings is the Way.

Even though charity and offering provisions can bring boundless blessings, the three evils in the mind still have a firm hold on their roots.

Hoping to offset their karmic sins with their blessings, they only find that in the future their karmic sins will still remain in spite of their blessings.

(The Platform Sutra)

As long as greed, hatred and delusion are present in the mind, there will be karma. The force due to karma will keep people in the cycle of birth and death.