The point is not whether passive voice has a place in good writing, it's to make young writers aware of the difference between active and passive voice, and when each is appropriate (or "strongest").
My point is that writing is like walking -- at first, you only have one way to walk, the one that keeps you from falling onto the carpet. Only later do you learn how to dance. It's the same with writing -- avoid obvious mistakes until you're skilled enough to use them for an intended effect.
That seems to be a different point or a muddled metaphor - people learning to walk are accidentally dancing (badly)?
I have not seen it established that passive constructions - where they are appropriate - are harder to use correctly or well. I have seen it asserted countless times, usually by people who don't know their passive from a hole in the ground and always without accompanying data.
