It is most likely impossible for a single person to know everything. No matter what the capacity of a person's brain is, it would not be able to learn and recall this huge amount of information. Therefore, for biological reasons, there are limits to what humans can know.
However, this does not mean that we should deliberately limit what a person can know. There should not be any limits to the information that a person can access, because by making knowledge available to all, our society and our whole world at large will benefit.