Are teaching on gratitude and "duty" nessesary?

Supreme Buddha once mentioned… >“These two people are hard to find in the world. Which two? The one who is first to do a kindness, and the one who is grateful and thankful for a kindness done.” — AN 2:118 **1. So my question to you is should Gratitute be on a par with Loving Kindness?** In other words, asked from another view point... **2. Are teaching on gratitude and "duty" nessesary for the path development?** Or even otherwise asked... **3. Is it possible to gain path and fruits for an ungrateful person, a person denying his/her duties?** **4. Could it be that the seldom appearing of gratitude is direct connected with the seldom appearing of people reaching path and fruit?** **5. What in particular are teaching on gratitude mentioned in the suttas? (References of Dhamma-Dana in this regard)** *[Note: This is a gift of Dhamma and not meant for commercial purpose and other low wordily gains by means of trade and exchange]*