Because most rely on their own wisdom, rather than letting God lead them to truth. Most people also rely on reading someone else's interpretation, carrying on answers that are taught and spread or being comfortable with reading something surface level, forming an opinion about it and leaving it there but with the possibility their initial idea could be wrong. The vast majority of people want information spoon fed, instead of actively delving into the word and trying to seek out truth themselves.
When talking to most people, the amount of gotquestions.org links I've gotten, or ones to just youtube videos is insane. We are told we have ONE teacher and that is Jesus. While hearing others opinions is good in a sense for correction, the main source should always be God himself. And sometimes that means accepting corrections that might be counter to whatever you've been taught. A lot of people also don't like being corrected.