It really isn't that hard to find them, but the problem is that there are a lot of people who don't like to search around places for them, because everybody will want to look in every little nook and cranny, to be absolutely positive that they didn't miss anything, and they don't like to think of it that way. There are also some people who don't know how to get to one and don't think enough or study the surroundings to get to it. Some people even miss the ones in extremely obvious places(right by you in dungeons, on the main path to a place, etc.). The problem is that most people aren't patient enough, and some don't want to concentrate on finding these things the entire game, which is what they feel like they have to do the whole time, and I don't blame them, if you miss one right along your path because you're too involved in the game it may be the last place you look, because you wouldn't think to look where you have already been and explored thoroughly.