Now, that I'll agree with. An absolute "never interfere" rule isn't wisdom, it's just using rigid legalism as a substitute for judgment. The point of the PD is to teach us humility, to help us recognize our own limitations and fallibility so that we don't blindly impose on another society in the name of what we assume is right. But as long as we have that self-awareness, we can nonetheless recognize circumstances where it can be valuable to offer our help, within limits.
This is definitely true. I never doubted at all the PD was well intentioned. There is definite harm that can occur when a technologically advanced society intervenes with a less so one. Our own history of colonialism is tribute to that. It was there to protect them from us pretty much.
But just because there are some times that we shouldn't intervene, that doesn't mean we should never intervene. I like the line Paris gave in one episode, "They're all going to die, what can be worse than that?" To which Janeway had no reply but to pull rank. Not intervening when a disease or natural disaster is going to wipe out a whole race, when the Federation could help, makes them in part responsible when they don't. The whole "moral" premise of Pen Pals, Homeward, really made me mad. Letting whole races die just because of a technicality and then calling it the ethical choice? That just baffles me.