Regarding the passive voice, the author is just providing general clues to good writing and is not imposing a dogma. Certainly the passive voice makes for a boring read.
So I think that his point is: get rid of adverbs for clarity, and change the passive voice to an active one to maintain interest.
I must say I agree.
What?? That makes even less sense than the "no adverbs" rule. Nothing in the syntax or semantics distinguish -ly adverbs from any other. (I only included -ly adverbs in my count because I was lazy and they were easier to search for.)
> Certainly the passive voice makes for a boring read.
You don't read much that isn't boring, then, eh? Too bad. Good writers use the passive voice. Writing that avoids the passive voice is not good writing.