This is literally the most important law we have, we founded our entire multiplanetary nation upon it. So don't worry if you don't follow it all the time. We're too busy prosecuting people for their parents choosing to alter their DNA.
You think Starfleet should be zipping around the galaxy, bringing their culture and beliefs to the primitive natives who haven’t even discovered warp drive yet?
No, I think that for instance when you have the power to save a civilization, probably without them even knowing, and you fail to act you have acted immorally. Having a blanket rule is the immoral part.