I believe the parent's point wasn't the accuracy of the information you'd be receiving, but just the exercise of evaluating conflicting viewpoints and coming out more enlightened as a result of it. Believe it or not, being able to apply that anywhere (as opposed to just thinking you can) is a skill, and skills need practice. It's an important part of thinking critically, and it can easily be lacking in a lot of very smart people.

EDIT: It wasn't my intention to offend if that was the reason behind the downvotes. It wasn't about anybody specifically, I was just trying to elaborate on a slippery slope issue that seems to be common among smart people.