She misunderstood to-be verbs and assumed they were only helping verbs (copula) in the passive voice.
State-of-being verbs are not the passive voice, although they are weak. I can think of no more natural way to write the following sentence: Even though it was October, the grass was green. (Yes, I used two state-of-being verbs). I could have written, Even though October had arrived. . . That's where personal preference comes into writing. But "grass was green" causes no problems to understand. It's brief and describes the status of a lawn.
I sometimes use state-of-being verbs,
but I'm aware of their purpose.
I distinguish them from the passive voice.