Say it loudly for the people in the back: Linking verbs are not passive voice.
(Someone on Facebook posted a ridiculous declaration about grammar, so I’m ridiculing it. Besides, the spreading of misinformation annoys the hell out of me, and somebody has to speak against these idjits.)
Look at this sentence: It was raining when Alice came home.
If you want to get rid of the linking verb was, you could write it in simple past tense as Rain fell when Alice came home, but that implies the weather was connected causally her arrival (rain fell because she came home), or at least that the rain didn’t fall until the moment she arrived, and what if that’s not what you mean?
Without linking verbs, we cannot have any verb tenses except simple present and simple past, and that would make severely limit how we tell stories or discuss real life.
Take a look at these examples of the various tenses (linking verbs in red so you don’t overlook them):
simple present: I like coffee.
present continuous: It is snowing. I am drinking coffee.
present perfect: It has snowed today. I have eaten too many cookies.
present perfect continuous: I have been fond of gingerbread my whole life. I have never liked cold weather.
simple past: I drank coffee.
past continuous: I was watching the snow all morning.
past perfect: I had given up coffee for a few months.
past perfect continuous: I had been trying to consume fewer carbohydrates, including sugar in coffee.
simple future: I will drink coffee.
future continuous: I will be writing tomorrow.
future perfect: I will have edited more than a dozen novels.
future perfect continuous: I will have been typing for three hours by the time my clone-sibling needs to use the computer.
Out of twelve tenses, only two do not use linking verbs. Are we supposed to believe all the others are passive voice? Seriously?
We can’t write/speak grammatically correct questions at all without linking verbs. Think about this, folks… You can’t say, “How did you spend the holidays?” without using a linking verb. You can’t even say, “What’s for dinner?” without using a linking verb. Does this not show that linking verbs are necessary?
Even if these were all passive voice (and they’re not — they don’t meet the “by zombies” criteria), that would be absolute proof that we need passive voice, wouldn’t it?
Also, notice the general lack of adverbs — certainly no –ly words — in the example sentences. If linking verbs cause adverb usage, where are they?