I thought the same thing when I was writing my essays at university, that it was an exercise in building a case by appealing to authority, rather than really trying to arrive at the truth.

Yes, exactly!

Looking back I do see value in the exercise though, but more in an indirect way. I think writing like this helps develop your mind by training you to weigh up and critically analyse different opinions, and come to your own conclusions and interpretations of them.

Doing this, I believe, did help me become a more critical thinker, and get me used to automatically seeking out and filtering through a large volume of information on any given subject.

Makes sense, perhaps that can help certain people, I just find it a lot of extra unnecessary work for nothing. I reference have various kinds of books, essays, and other writings, but I don't feel the need to cite them unless it's something I want to point out goes more in depth than what I can or wiling to do.