So you are saying, if there is two ten out of ten pieces, one a creative and another an expository, then they are both equally good? Well, that logic doesn't work because we all know the standard marking is that every piece is marked from a scale of a 10, or a 100, or whatever. Both may deserve the mark of a 10/10 in the given cohort, but that does not mean both pieces are equal in quality.
"furthermore, why does Expository continue to be popular amongst students if it's that hard to score well in."
Because it is more accessible and perhaps because writing a good creative which links to the prompt and the ideas which it requires is just too damn difficult under one hour. Why do you think most ESL students pick Expository in the exam? Because it is relatively easy to write a decent expository, than it is to write a decent creative. And why? Because creative pieces usually need more thought, and therefore more time, and it is more demanding in the language department. Why is that so? Perhaps, in part, it is because of the culture, or the era where we live in, a time where students are more comfortable with consistent, formulaic and systemic type assessments.
" Just because your tutor told you something doesn't mean that it's true. "
Honestly, I don't know where you are heading. If you want to go to the philosophy bit about truth and knowledge and start question your very existence, that is one thing. But from my knowledge, this is an advice thread, and we give advice as we see fit- as best and as honestly as we can. Like I have said before, I have only given a strong expression of my honest opinion.
"In my view and according to what I've read (Assessor's Reports...etc.) you should choose the form you are most comfortable writing with."
You said it yourself, and I agree. You just answered your previous question. They are more comfortable with it, however, as a consequence, the competition is likely to be stronger to write a standout expository piece.