Optimism/Pessimism/Realism

I was recently sent an article about Optimism / Pessimism / and Realism.
I don't agree with the article, and would like to express my thoughts that are summarized as follows: 1) Pessimism is misunderstood, and 2) Realism does not exist.

Pessimists: The article describes pessimism as when a person is “more likely to look at the negatives in a situation and are often saying things like ‘if only I had’ and ‘I should’ve’”.
My reaction: I don’t entirely agree. Pessimism as defined by Merriam-Webster is “an inclination to emphasize adverse aspects, conditions, and possibilities” but not necessarily to solely expect the absolute worst. Phrases like ‘if only I had’ or ‘I should’ve’ do not describe or encapsulate pessimists. Why would someone say, ‘I should’ve’ (an after-the-fact statement) if they’re already inclined to believe adverse possibilities are likely to happen? It sounds like an edge case, a lack of foresight, and a high degree of spontaneity or loose living (these are inferred by me - creative control I'm granting myself as the author of the article loves to infer).

A team full of pessimists: The article states, “If you had a project team full of pessimists they wouldn't get very far past their first concept because when everyone is pointing out faults and mistakes it leads to discouragement and a lack of motivation which would cause the team to work slowly or even disband.”
My reaction: I don’t entirely agree. I would rather work with a team of pessimists than have one optimist on the team. How is pointing out faults with the first concept going to cause a pessimist (a person that already is aware and believes in adverse possibilities) to derail their project? That would be like Superman getting derailed when he realizes he can lift a small car with ease. Duh, that's kind of your thing.

Realism: According to the article, realism is “the middle ground between optimism and pessimism while also including optimism and pessimism.”
My reaction: I don't believe it exists, and it’s definitely not provable.
Example: Let’s boil this down to the simplest form. An optimist believes that the snake-oil that they just purchased is going to cure him of his ailment. Regardless of outcome, this is what he believes.
A pessimist believes that the snake-oil that the optimist just purchased is NOT going to cure him of his ailment. Regardless of outcome, this is what he believes.
A realistic believes what exactly? That the snake oil will cure the optimist? No, that would be optimism. That the snake oil will not cure the optimist? No, that would be pessimism. There is no middle ground in the simplest of forms. Any perceived gray area is already covered by both elements.

Plenty of people claim they are of a ‘realist’ mindset, but they don’t know what they’re talking about. No one walks around on a college campus claiming they’ll be okay if they pass or fail a test. You either desire one or you desire the other, otherwise why even take the test?