If you are a leaf, your ultrapeers will only send you only those queries that contain keywords matching files you are sharing (that's not always accurate but it saves easily 95% of the traffic between leafs and ultrapeers). Ultrapeers are not shielded that way (or at least they were not shielded when that FAQ was written) so they can see much more queries in their montior window.

So, if you want to see what other people are searching for you'd better become an ultrapeer.