Limited capacity

“As we saw last week, Sweller’s Cognitive Load Theory proposes that different types of memory have limited capacities.”

This theory surprised me the most. With all these years of experiences, I thought human’s brain can handle a mix of different types of information, but we only have limited capacities for these pieces of memory?? Whaaat? But this also explain that why some people are excellent in one area, but not as good in other areas.