I'm sure you have used reputation a thousand times in your life to decide whether or not to dine in a restaurant, take a class from a professor, or stay in a hotel.

In my college experience, many courses that came highly recommended by the student population were garbage. Students don't have the experience to judge the worth of all courses, and the same information and knowledge asymmetry extends to many other fields of human activity.

Mostly highly rated classes tend to be blow-off classes, rather than informative and engaging ones.

All of those things are subject to substantial regulation, meaning that it's not that much of a risk to eat at a restaurant I've never heard of before. And even with those lower stakes, plenty of highly-rated restaurants I've been to turned out not to be so good.