I haven't run through the statistics, but the three most commonly closed questions are:
There are a lot of questions are almost identical to previously asked questions, or at least the context similar enough such that the previous answers would apply. I'd hazard a guess that questions about relieving letters would be the most common.
These questions clearly are asking for legal advice, which is obviously beyond the scope of this site for risk mitigation reasons (and is enshrined by Stack Exchange). While some ask for help on a particular regulation (which can be found easily enough with a quick Google search and are not off topic), most should be talking to a legal professional.
Advice on what to do
Many people have a choice of two paths. They can't decide, so they ask the Internet. How can we possibly know their situation, their aspirations, their goals in a few lines? They would be far better off talking to friends or family who know them.
The other two close reasons are not so commonly used. Compared to the top three, they comprise only a minimal amount of closed questions.
What this all means!
Duplicates are almost always immediately obvious so. When the questioner is formulating their question, the suggested list of questions almost always would clearly indicate that the question has been asked before. Obviously, they are not paying attention to it.
For legal advice and advice on what to do, it's already clearly stated in the Help Centre that these are off topic. Without adding flashing red lights, I can't see how it can be any more obvious.
I believe that the guidelines are clear enough, however people simply don't read them. The reason so many questions are closed is because people are either not reading or ignoring the clear guidelines that are already there.