What's wrong with the question and how can I make the question better to have chance for answer?
ChrisF hit it on the head. Your question is overly broad; answering it would require an explanation of everything from networking technology to hardware interface design to operating system construction.
An evidence of this problem is the fact that you have linked to Wikipedia is an encyclopedia, its entries are intended to be summaries or overviews, like a more detailed descriptive dictionary. You seem to be confused about the nature of Wikipedia. It would be much better if you'd referenced an entry in the PCIe specification, a $5,000 set of documents which describes all of this this in great detail. If you read those documents, then you would know the answer to your question. However, acquiring the knowledge required to read these documents would likely take a lot of education that you don't evidence.
That's not fair that it was closed by the same users to have interest in spoiling the possibility of answer (in another question) and without discussion.
Is this behavior (censorship with no discussion) good for free knowledge sharing?
You seem confused about the nature of Stack Exchange. This isn't a place for "free knowledge sharing", it's a place for objective Q&A. To have the best possible repository of Q&A, we must necessarily disallow subjective, unanswerable, off-topic, localized, or otherwise problematic questions.
I closed the question without adding a comment myself because the close reason and other comments fully explained my reasoning.
Another question of my questions was closed, though it was answered and the answer was very good for me and believe that will teach many others. It had upvotes before the evil close-users noticed it.
That question was also overly broad. The presence of an answer does not mean that a question is useful.
Occasionally, if users have invested significant time and energy and have crafted a great answer for a cruddy question, we'll edit the question so that it is suitable and let it stay open. In this case, the question could not be salvaged.