It is much more reasonable to me that if you want to know what someone said, or how soemthign is, you'd go to the source and find out directly...but instead, they find all these obsure people who are giving their own opinion on said subject and take it as truth.
But what do we do when we don't have the source? What we have is a multiply translated book that is attributed to a writer. In antiquity, it was often the practice of attributing something by a lesser known writer to a more famous one, so taking the "byline" at face value is a bit naive.
Also, to really understand what a person means, you have to do more than just look at what they wrote down. You have to learn the idiom of the time, you have to try and figure out allusions that may have been obvious to people of that time but which mean nothing to us today, and you have to try and figure out if they were speaking sincerely, satirically, or with a hidden motive.