I was telling a friend of mine about the SO/SE model today. At some point he asked, "wouldn't you want to somehow separate questions according to the level of the target audience?" That is, if I'm an expert on foobar and I visit SO, the most popular/most upvoted foobar questions will likely be the kinds of questions that students think about when they take foobar 101. The really niche-y questions that would appeal to a foobar expert like me will have few views/upvotes, so they'll be hard for me to find. My friend was suggesting that maybe expert-level questions should somehow be tagged as such. I think this is a bad idea, but I can't exactly put my finger on why.
Does SO appeal to experts looking for interesting questions, or only to those experts who are willing to comb through pages of newbie questions? If it appeals to (non-persistent) experts, how does it do it?