There are surely some details missing
That's what makes it "unreal". The question can be re-opened after those good details are "subsequently added." Until then, any answers are just guessing at the actual problem.
If a question is missing important details, it should be closed until those details appear.
How are the newbies supposed to know this (when it wasn't obvious to me)?
This is a matter that has been discussed quite frequently, but no movement has happened on this. I think that changing the term "closed" to "needs work" for "Not a real question" closures would help in this regard.
The current situation is not ideal. But it's not sufficiently bad for the people running the site to actually do something.
Why can't this be clearly said in the reason for closure?
The message is relatively clear on the subject. The reasons for closure is clearly outlined. The very first sentence explains the general problem: "It's difficult to tell what is being asked here." And from the question, it is difficult to see what is being asked.
Remember: we can't have 20 different slightly different closure reasons, each one explaining one of the possible things that could be wrong. "Not a real question" groups together several generally fixable problems with questions.
A balance has to be struck between the needs of the person having their question closed and the needs of the people closing them who need to be able to quickly and effectively deal with garbage questions. I certainly don't want to have to click through a drop-down just to cast a close vote.
The newbie probably has no idea what details are relevant anyway, nor do they know how to find them out
Then we can't help. We will not play 20 questions with a new user just to get them the help they need. Q&A means Q&A: ask a practical, specific question, and you'll get a real, useful answer.
The complete newbie doesn't need Q&A; they need help. And it's important to understand the difference between those two things. Help means guidance from someone who is going to provide a dialog. Q&A isn't about dialog. Q&A is antithetical to dialog.
Remember: a lot of us have fled forums because we don't want to provide "help". We're tired of providing "help", particularly to people who don't seem to want to try. We just want to answer questions.
Stack Overflow is not meant to be for everyone who programs. It is meant to get answers to specific programming questions. If you don't know enough to ask a specific programming question, then you will need to avail yourself of forums or other resources until you have learned enough.
Looking at the linked question makes clear that this site lost a potential user. This site has a lot of users, so you might not care....
Ultimately, The Powers That Be don't care about one new potential user. SO is not the most newbie-friendly site for programming help. The newbie who needs help is not the person we want here; we want a programmer, of any skill, who has actual questions.
There is no ideal solution. The current state of things could be improved, but there will always be people who don't meet SO halfway. The only way to maintain a level of quality in questions is to close those that do not meet our standards. This means that it is incumbent upon the person asking the question to ask a good one, or suffer the consequences.