I certainly can't (and won't) speak to the specifics of the programmers site, but would offer an analogy that helps me know when and how to close and migrate a question on the site where I'm in a position to do that work.
I look it your question as "Is it a problem that the police are writing tickets against 30% of the drivers on road X last month?"
No - the ticket writing isn't really a problem and instead you'll need to focus on the behavior of the drivers that is causing this ticket rate.
- What percentage of the drivers being ticketed even went through training? (Are the guilty clearly breaking a rule)
- What percentage of drivers are exceeding the posted limits? (Is enforcement getting most of the offenders)
- Are the signs even clear about what the expected behavior is? (Even when you don't catch everyone, seeing those lights by the side of the road regularly helps to shape future behavior of the community)
So, this analogy gets a little strained - but looking deeper at your closure rate will illuminate the good and bad tradeoff that is happening in your specific site. The good of course is a low barrier of entry to ask a question. The bad is time and energy to deal with questions that didn't land "in bounds."
By seeing to where the good questions are migrating and from where the bad ones are originating, you'll start to have an answer if one or more problems exist by looking at these groups over time.
If the questions being closed are bad - then awesome! Selective moderation(in the sense that the community is correctly eliminating garbage and garbage only) is the lifeblood of good content on all of the SE sites.
Do you have a sense if the community is able to close these questions or this effort lies in moderators stepping in with a super vote to close? When the strain of moderation is so large that people are doing pointless work closing, then you might want to look at what sort of people are asking these questions and work on making the "rules of the road" more clear.
Having a high rate means the next step is to measure things a bit to determine if there are patterns to the closures. Once you write off the bad questions, you can then focus on the good questions that got asked in the wrong place for something actionable you can change or work on as a community.