By saying that the questions have a difficulty level, you seem to be assuming that they have a concrete answer. I value our discourse more than wrong and right answers for these questions.
Wtf, while yes, you are absolutely right that we all will be more versed at one subject or another, after giving it more thought, I'll clarify my personal answer:
There are certain subjects that I have no use for or that bore me to shreds. There are subjects I wish I knew more about for one reason or another. I like the idea that I can look to a partner to educate me in his/her subject area of expertise and feel like I am being challenged intellectually and therefore grow as a person because of them. I'd also hope for the reciprocal of that scenario. It's the idea of balance that I enjoy, therefore complimenting each others' intellectual strengths and weaknesses would be ideal for me. And YES, I admit that some subjects can bore me to shreds, and it would make it difficult for me to enjoy a conversation. That is what friendships with other people are for. If something I take interest in bores my partner, I have other friends I can share that subject with. This brings to mind another topic for discussion. Can we really expect one person to satisfy every mental or intellectual need? I personally think not.