Perhaps they do not know better.
You can use the discussion area to expand your question, so people know more about what you're asking.
Most questions get satisfactory answers straight-away, so there's no need to use the discussion area. It's beneficial to use the discussion area if you need to explain more detail about the question being asked.
Yes, you may use a question's Discussion page to comment othe question's answer.
The Discussion page of questions is to be used for notes about the question and/or the answer. Supervisors sometimes use the page to add notes to the answer that should not be added to the answer itself, however the discussion pages are used very seldom.
Use the discussion area.
Yes, WikiAnswers does have a user base in China.
Curious people use WikiAnswers, along wiht many other kinds of people from all over the world. Curious people want to know an answer to their question, so they go to WikiAnswers to find the answer. There are many other types of people who use WikiAnswers, in fact, millions of different individuals use WikiAnswers.
Discussion is to be used for conversations about answers and question. Question askers may use it for clarification or exposition to help with answering.
Brands can have account on WikiAnswers. Anyone can have an account on WikiAnswers. You cannot use WikiAnswers for spam; it is to be used to only to answer questions for people or ask questions that people may want to know.
Please use the Discussion area to be more specific.
Wikianswers helps people by giving them answers to their questions. In addition to that, your frequent use of wikianswers will make you more knowledgable.
Anyone can use WikiAnswers that knows about WikiAnswers.