I think that the statement is absolutely correct when one looks at Sophy's life. Hardy depicts Sophy as an individual whose will is crushed in many different ways. The institutions of marriage and motherhood as well as religion help to play a role in denying Sophy her wishes and crushing the life out of her. Sophy is bound by marriage to honor her husband, even if it comes at the cost of her own desires. At the same time, Randolph is able to gauge the level of power he holds over her as a son in a society that values patriarchal notions of the good above all else. Sophy finds herself crushed between honoring promises that Randolph demands of her and her own wishes. When Randolph makes her vow, on her knees and in front of a cross, that she is to never marry Sam, it is a moment in which one sees how her will is crushed. Sophy's entire life is spent waiting for something that will never materialize.
Sophy waits for her own dreams and hopes being acknowledged. She waits for the light of her wishes to illuminate all. This light is doused with the expectations of her marriage and then her son. The ending is one in which death becomes the sum total of this wait. In the ending in which the man she loves is left to watch through the disapproving glares of her son, one sees how Hardy's fiction has effectively crushed Sophy. Death becomes her release from a condition in which pain and suffering are the byproducts of hope and want.