Jim — Of course reality is not tidy. If you interpret “do no harm” to mean the government should literally not do anything unless literally no one is made worse off, then you have a recipe for total stasis. You could not undertake any policy initiative, whether progressive or conservative. Introduce a carbon tax? Might hurt some kid whose Dad would have to change from running a gas station to running a charging station. Water down CAFE standards (as Trump administration plans? Might hurt some kid whose Dad has just spent money to add a charging station to his gas station.
What you are advocating is the economic policy equivalent of Janism, the Indian sect that carries the sensible precept “Thou shall not kill” to such a point that they wear a mask in order to avoid the risk of inhaling and killing some small insect.
I am not persuaded.