Some questions are closed as duplicates but mostly when I search randomly, the duplicates that I find are helpful. So why are they closed as duplicates? Even when the question is edited, moderators don't pay attention even if the question wouldn't be a duplicate any more, still they leave them closed as duplicates.
closed as unclear what you're asking by Wrzlprmft, Nathan Tuggy, Glorfindel, Shadow The Dragon Wizard, Patrick Hofman Feb 3 '17 at 7:02
Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
Duplicates are good because they are marked as duplicates, acting as a signpost to the other questions. See How I Learned to Stop Worrying And Love Duplication.
Your implication that duplicate questions are a good thing but a question being closed as a duplicate is a bad thing is simply wrong. Without the question being closed there is no link between questions and you'd end your search on that question, limiting your chances on getting a good answer.
If you're unhappy with existing answers then there are other ways of bringing attention to existing questions; see What should I do when there is a question that is the same as one I would ask but none of the answers answer my question? and What if my question is technically a duplicate, but the original question was never answered? for example. Purposely asking a duplicate and complaining when it is closed as a duplicate isn't the way to go about it.
If a question is edited to a point where it isn't considered a duplicate, you can flag for moderator attention or ask a question on the sites meta to bring attention to this, make sure the question is significantly distinct though and explain your reasoning as best you can. If enough users with sufficient privileges agree with you then the question will be reopened. It's also worth noting that generally speaking it is regular users — not moderators — that close and reopen questions.