A PBOK is your personal book of knowledge.
In the world, today, to get ahead and to stand out you need to be creative. You need to bring a unique perspective to what you are engaged in. Simple knowledge is no longer enough, anyone can look that up on the internet.
Your PBOK consists of what interests you, what you are pursuing, as well as who you are, and what you bring to the table. It includes your experiences and history. This information that you constantly evolve and add to is what gives you a creative edge. No two people would create the same PBOK and therefore no two people would come up with the same creative ideas.
Building an effective PBOK is not only what you put into it, but also how you organize it. Th whole idea of a PBOK is to be able to get information and valuable creative ideas out of it. The better the structure and taxonomy the more you can get out of it.