"Do no harm." isn't wrong, just insufficient. In order for freedom and responsibility to be meaningful, people must be able to make decisions such as what is harmful for themselves. Additional guidance is needed for the practical application of it.
Also, it's negative ethics - what not to do. I propose the positive correlate - Noblesse Oblige. In its ordinary form it means the duty of society's "elites" to those under them. I propose it be extended universally to mean that in whatever way you are privileged you should help those who are less fortunate. For example, beautiful people owe some moral obligation to the ugly, happy people should help the depressed, and yes, the rich have a moral obligation to reduce poverty.
That does not imply that some nameless government bureaucrat should decide how those prescriptions should be used. It is necessary for practical reasons at least that everyone work it out for themselves.