> The thing performing the verb may not be relevant or may be actively distracting to mention.
That's exactly what I was thinking when I mentioned my Chem 101 lab reports.
I tend to write in a passive voice and if I read my words out loud rather than silently, it's obvious to me. It's almost sounds like I'm using cop talk (the subject was observed exiting the vehicle).
Passive voice hides the thing that is performing the verb in the sentence. That obscurity has some costs. It tends to make the sentence longer. See "benefits most writers" above instead of "is beneficial to most writers".
Worse, it tends to make the sentence harder to "get into". You want the reader to concretely visualize what you're saying. When the sentence gives you no actor to place in the scene, it's harder to grasp what's really going on. That vagueness in turn makes your writing harder to understand and harder to remember.
On the other hand, sometimes you really do want to hide the actor. The thing performing the verb may not be relevant or may be actively distracting to mention. It may be that one or more actors may be the thing that performs the verb and you don't know which one it will be. Being specific could be incorrect. In those cases, I think passive voice is fine.
But as a first approximation, "avoid passive voice" is good advice. Be skeptical of every use it, and don't be equally skeptical when you use active voice. But don't tie prose in knots trying to avoid passive voice entirely. Sometimes an "is" is fine.