I know the difference between content-based and collaborative filtering approach in recommender systems. I also know some of the articles said collaborative filtering have some advantages than content-based, some of them also suggest to use both method (hybrid) to make a better system recommendation.
Is there a specific case where the use of one method (content-based, specifically) is better than another? Because if there is no case at all, why both methods are considered to be on the same "level", why not focus on just one method? For example, focus on collaborative filtering or hybrid method (as an extension for collaborative filtering).