Cerumen will thinly coat the ear canal to protect it. When you mess with that flow, you create little build-ups, kind of like road traffic. This accumulates and create the equivalent of a traffic jam.
This is also why Q-tips users swear by them: they are creating the issue that requires the Q-tips in the first place.
Worth noting that not all humans have the same kind of cerumen. There is wet cerumen (dominant, 50%) and dry cerumen (20%). It depends on your genetic. If you are asian, chances are that your cerumen will be harder and require scooping out. Again, this is done with a little spoon by a third-party or by using one carefully (they also come with cameras and flashlights). You remove the build-up with accuracy, you don't just jam cotton in there and randomly scrape at your ear canal.