Stack Exchange sites are generally concerned with asking and answering questions that can be answered in a fact based manner. Meta is entirely different. Meta allows, and even encourages, questions that are opinion oriented. Questions in the form of "I think X should be true/modified/created. Do others agree?" These questions don't lend themselves to a universally "correct" answer. Furthermore opinions can evolve unlike facts.
Duplicates on meta are not the same as duplicates on the main site
I completely agree that a few people or one moderator should be able to close questions on Stack Exchange sites, but I feel the bar should be much higher on Meta. If gold badges/moderators aggressively close questions on Meta it stifles people's ability to discuss issues. Some questions are rightly closed as duplicates like my first question.
There are also questions that are shut down by people who feel that an old solution is sufficient or a previous discussion should remain cannon eternally. This is encouraged by the Q&A format, after all if the question has been asked and already answered why should it be asked again? The voting system that is so effective for factual answers also serves to inhibit evolving opinions over time. For example if I post a new opinion to a Meta question with 10+ answers a year later my opinion will realistically never be heard. This is especially true when gold badges/moderators tend to aggressively close a new version of the question as a duplicate, and actively encourage people to post answers that won't be viewed.
This very question is an illustration of the problem
This question was aggressively closed in minutes (~15, and before I could respond to a comment mentioning the duplicate) because a gold badge thought my question was a duplicate. Notice that I mentioned that quick closes, and allowing space for opinions to evolve are in my question but not in the duplicate. I brought these new reasons to my question but it was still closed. This highlights why I think single person closes are antithetical to the goals of Meta (also in my original question and not in the duplicate). As such I feel my question is a clear example of a "shallow" duplicate that was needlessly closed.
Also as enderland mentioned in the comments below: I understand this is currently the best tool we have. Just because this is the best we have doesn't mean we can't talk about the best tool to replace the current tool, even though replacement will naturally take a good amount of time....
Proposed solution: meta should be moved to a forum-based system rather than Q&A
Due to these reasons and more I suggest that Meta moves away from a Q&A format to a format that encourages discussion, and away from a format that encourages immutable canon answers. A solution like Discourse comes to mind as an option, but I don't think that is ideal either.
Edits based on responses by others:
Hamlet made an excellent point when he said that Meta exists for two interrelated purposes. It exists to discuss policy, and to document policy. My question is scoped at duplicate-closing when discussing reconsidering current policy.
In a comment below James asked:
[W]ould you say re-open by "one moderator" is ok? Surely it's the same logic, even if just a different problem. Close by 1 user = no discussion (or democracy); Re-open by one user = no democracy or allowance for "no" discussion from the people you want to "not" allow to close.
For full disclosure, this question was reopened by a moderator and James supported closing it. I do think that it should be easier to reopen questions than to close them on Meta. Obviously issues in Meta/Stack Exchange aren't nearly as important as criminal cases in the USA, but I'm going to use an analogy that I think is relevant. In the United States one judge or a handful of judges can reverse a decision made by twelve jurors, and other judges. This is true, at least in part, because there is a recognition that a wrong conviction is more damaging than overturning a valid conviction. The reason I support more arduous duplicate closing and easy reopening is for a similar reason. I think it is more valuable to the site and the users to have a discussion that may eventually be merged into another question as a duplicate than to prevent the discussion from happening.
Also in the comments Nathan Tuggy made a great point when he observed that:
For what it's worth, meta dupehammers are far easier to come by (since all questions must have at least one of four tags, and are therefore vulnerable to gold badges on those tags, which are for the same reason also much easier to get).
This is very accurate. A byproduct of Meta's design makes it far easier for active users to earn the power to wield the "dupe-hammer" on Meta than a normal Stack Exchange site. To paraphrase a common expression: "When you have a hammer in your hand every idea you disagree with is in danger of becoming a dupe." When questions can be closed off-hand immediately by one person without considering the (potential) nuance of question everyone loses.
To support the age old saying that, "There is nothing new under the sun" random kindly suggested no less than 5 duplicates of the latest version of this question in a single comment. I assume this question wasn't re-closed as a duplicate of one of those due to the respect that Shog9 (who provided a great edit that refocused the question on the issue that caused me to pose the question initially) has in the community.
Good title match, but a bug duplicate is a very different question than evolving policy questions. One of the answers to this question suggests offering a bounty on an existing question, but that doesn't work if you feel your question is distinct from an existing question, or if a duplicate question to yours was incorrectly closed as a duplicate to another question due to superficial resemblances.
Another couple good title matches, but the questions and responses are clearly scoped to the Stack Exchange sites.
The title says it all. This question is pondering the validity of a specific closure.
This question is pretty damn good duplicate of my question. It captures the rage I've seen expressed in chat about meta, and the apparent futility of fighting for something on Meta. The problem with this as a duplicate is two-fold. One I can't respond to/bounty/interact meaningfully to/with it because it was mistakenly (in my opinion) closed as a duplicate for a question with a different scope. Secondly the OP sounds like they want to endlessly debate due to the wording of their question as captured in the response by Shog9. I'm not suggesting that people should endlessly debate. I'm suggesting that we allow people space to develop an idea without being prematurely shutdown based on a superficial appraisal.
A person's question might be a duplicate, but for continuity of the discussion, and moral in general it is important that the right duplicate be found. False duplicates only mislead, and frustrate users.