There is a limit to the amount of knowledge you can access when you first begin studying. Because you're open and there's not much to absorb, you're like a sponge, soaking up everything.
Access to information ceases to be a constraint very quickly in primary education. Once you bring home a few massive textbooks, the bottleneck shifts to how you organise and contextualise the knowledge.
There are many different ways to organise knowledge in high school, from outlines and diagrams to reports and essays to notebooks and binders. Your inability to assimilate this data and generate new ideas becomes the bottleneck.
If you make it through college, the bottleneck shifts to the development of new ideas. When you begin to investigate the world around you, you discover that the best intellectual benefits come from ideas that change your perspective of it. You begin to search for the revolutionary, the contentious, and focus on unravelling paradoxes and contradictions.
From there, the bottleneck shifts back to your assumptions. They limit your ability to think and act by constraining your perspective. The discovery of new assumptions and the illumination of blindspots that you didn't even know you didn't know about becomes addictive. All of your preconceptions can be disproved if you examine them long enough.