For a couple of decades now college professors have been death on passive voice sentences, which tends to create students and then writers who avoid long sentences for fear they aren't "punchy" enough.
> … it makes little difference if you decide to look at prose written by the advisers on usage themselves. Consider the beginning of E. B. White's introduction to his revision of The Elements of Style (Strunk & White 2000). I underline the head verbs of the passive VPs … Six instances of transitive verbs appear here: took, called, required, called, known, and printed. Five of them are in the passive. That's over 83 percent.