Thoughtful article.

Merit-making really has another name: pride, & perhaps vanity.

Pride is putting one's security in oneself, the ability to control events, the outcomes, etc. 

Vanity is putting one's security (sense of worth, well being, etc.) in the opinion of others, what others think of you. Reputation.

(Sensuality is another defect. It's placing one's security in the things of this world.  Food, drink, sex, "experiences")

By virtue of original sin, people will have these struggles for life at some level.  They can be and need to be tempered, but in some form at least one of these ("the dominant defect") will be popping up until we die.

So the practice of "rectifying" our will is a helpful thing for Christians to do, occasionally examining the why of our behavior.  Why do we do the things we do?

The rectified will does things for the love of God and the true good of his/her neighbor. 

This actually makes life much easier.   The hard to do become the "hard and sweet" to do.