Dostoevsky and Hemingway are known for their prose and conveying human experience, not their political theory and speculative fiction. I think Rand’s story-telling is better than Slate gives her credit for, but we’re hardly discussing the value of her prose.
In other words, Dostoevsky and Hemingway describe the human condition; Rand makes diagnoses. If I criticize Rand for making false diagnoses, it’s silly to say that Dostoevsky and Hemingway aren’t medical experts, either.
Your use of the word "diagnosis" is a straw man - one could just as easily ask where Rand purported to be, as you put it, a "medical expert." The "human condition" that Dostoevsky and Hemingway describe is that of the individual fighting against personal cowardice and relying on their own integrity rather than giving in to coercion and fear. Dostoevsky, especially, pits people against these things as represented by government tyranny. These "human conditions" are identical with ALL of the focus of Rand's work. To separate Rand - to separate The Fountainhead and Atlas Shrugged and the singular focus of Objectivism to protect against collectivist tyranny - from the "human condition," is not only absurd, but deliberately disingenuous.