Your take on my example does not make sense. In extreme cases like starvation, destitution, homelessness etc. aid workers don't rank the needy on a "attitude scale"; they simply provide the needed services to alleviate immediate suffering in order of priority if applicable.
I think you are trying to argue the inarguable. The reason i feel so strongly about these kinds of platitudes is because they have a) not solved the problem b) caused more harm then good due to wrong interpretations and applications.
As another direct example from HN threads; many people are disheartened because of not being able to land a job in spite of having gone through hundreds of applications and interviews. Here again it is far more important to help them evaluate themselves dispassionately (eg. lack of needed skills, bad communication, non-existent networking etc.) vis-a-vis the competition/market needs/etc. in a clear-eyed manner than just asking them to "be positive" and leaving them with a pat on the back. You need Actionable items and not merely Advice.
We are social beings. So imagine two starving people, one has a good attitude, one doesn't. The one with the good attitude is more likely to be admitted and kept in the good graces of a social network that helps them when starving, the other is not. So the good attitude helps in this thought experiment. The issue with your thought experiment is that it takes each man as an island.
We don't exist in a vacuum, we are not islands.