I read the entire thing, and I'm still not sure why he bought an encyclopedia. It seems like the stated main reason is so he can talk to his kids about how different sources are written and constructed. A noble goal, but it seems like a paper encyclopedia is pretty incidental to that goal.
Quite frankly, it seems like the real reason is the author has nostalgia for his encyclopedia growing up, and wants his kids to experience what he experienced as a child.