Why is "Negative Additude" a report option?
Why is being a pessimist against the rules? Why is having low morale and giving up against the rules? Why is not trusting your team in Solo queue against the rules?
Why should a person be punished and possibly banned for these simple things? The only time being negative might be punish worthy is when you step the line and verbally abuse someone by blaming. But if you are simply giving up, so what, the game isn't going their way you cant force someone to be happy about a bad situation, and telling someone they are negative isn't really helpful either.
Once someone has had an emotional response, telling them that they are that and to stop that is like slapping them in the face.
No one likes losing, it is a negative experience it will be met with negative emotions. Everyone will deal with it differently, so why punish them for it?