Firstly, we need to see the exact wording of the real question, and I guarantee you 100% that, "why go to university" is not a TOEFL Writing Section question! Something more like, "Some people prefer to study in universities in person, and others prefer studying online. Which do you prefer and why?" Or maybe, "Some people believe that online education has the same value as traditional attendance. Do you agree or disagree with this idea? Support your opinion with reasons and examples."
The first step in evaluating a TOEFL Writing response is to know the task. In this case, we are unable to know what the task really was. If you would like help in the future, I would suggest quoting the exact question from a reliable TOEFL resource (like Bruce Rogers, Cambridge, Longman, ETS, etc.), so the rater can know how well you have completed the task, as this is a major factor in scoring a response and offering advice. Best wishes.