I agree that the question is overly general, as has been pointed out (and Jerv explained why). But I think the answer lies within that concept of generalization—if I ask one person his/her opinion of something, I get his/her opinion. This may or may not be the thinking of all such people. If a magazine does a survey, I get a sense of the average thoughts (not one person’s thoughts) or I can see that 45% of men responded in x fashion. It can give me general ideas on a group’s responses to a topic.
I can ask direct questions of specific people if I want to know more about the specific person, but sometimes I am trying to understand the thinking of the group. There are patterns (when taken to extreme we call them stereotypes). Think about how many emails you receive that show cartoons or stories about “Men and how they think” or “women drivers.” They aren’t even funny but we can sometimes see elements that support our own experiences and beliefs (also true with the magazine surveys). I think it is a way of assuring ourselves that we, and by extension, our thoughts, are normal.