Objectively you're right, but I hope you think twice before saying to someone who has experienced a tragedy, "You need to move on." Similarly if you're in an argument with a friend or loved one and they are upset I hope you think twice before saying "You need to calm down" or, "You're overreacting." Objectively those may all be correct, but they are unhelpful, and are likely to have the opposite effect. They minimize the weight of the emotions. Most of us cannot just turn emotions on and off, much as we try and wish we could.