What's wrong with Capstone?

I don't see any purpose. Capstone professor are telling us to write something which we don't have a lot knowledge about. It is getting on my last nerve. Last semester, we did research for our topics, so we can come up with the end product. But they rejected 90 percent of the end products at the end of the semester. They wasted our entire semester. I took nine classes last semester. I had a lot of homework which had capstone research assignment on top. I don't know why we have to take this class. We can never come up with a perfect end product because we have very little information.