Metta towards yourself - useless? There is a part of Yuttadhammo's answer at 

How to practice Metta without a Benefactor? 

that has very confused me:


  cultivate metta towards yourself (useless, but a good example)


Why is metta useless? 

Are there any specific sources for this statement, or is this based on a determine school?
I think this needs qualification. 

Metta towards oneself helps reduce self hate. So this is not completely useless. Also this is the basis of developing Metta to others. If you do not love yourself you cannot love others. [page 83 Knowing and Seeing - 4th Edition by Ven Pa-Auk Sayadaw]

You cannot attain Jhana if the person is oneself, hence as a means to achieve Jhana this is useless. [page 82 Knowing and Seeing - 4th Edition by Ven Pa-Auk Sayadaw]

Other objectives is as an antidote to hateful temperament towards others. On this perspective this is useless if you contemplate about only oneself and not of others, but useful if you contemplate about oneself and others. As you cannot love others if you do not love yourself hence oneself should be included.

Also this is used to break barriers [page 85 Knowing and Seeing - 4th Edition by Ven Pa-Auk Sayadaw] as perceiving someone dear, neutral and foe. In this perspective it is useful to asses the level of love to oneself vs loved one vs neutral people vs foes, but not useful if you contemplate only about oneself and not others, and only others and not oneself, and useful when you contemplate on oneself and others.