I'm inclined to agree with your sentiment, but the example given doesn't quite sit right with me. "Often a sentence fragment missing a verb (like this)." vs

I'm inclined to agree with your sentiment, but the example given doesn't quite sit right with me. "Often a sentence fragment missing a verb (like this)." vs "Often a sentence fragment is missing a verb (like this)." We still have short sentences which seem to make sense without a verb. Is the following grammatically incorrect? "Hello there!"