The full context in the article says that this only applies to the specific task of analysing a screenshot and answering a user prompt based on the information

The full context in the article says that this only applies to the specific task of analysing a screenshot and answering a user prompt based on the information in the screenshot (and some other things). It is fair to say that a small model that can run on the iPhone won't have the world knowledge to compete against GPT4 but it can be better for something like this specific task.