My answer: maybe people really believe that this is the best approach to everything. I think most people mean well by giving this answer. People probably mean to save time and keep things interesting. I have gotten exasperated, myself, when people have asked me very general or simple questions ("what are some Jewish holidays?" "How to you make green tea?") and I've told many people to go use Google.
But I am finding it tiresome and nattery. And I wonder what those replying "google it" so frequently think about the depth and intricacy of information which often turns up from discussing, rather than simply googling.
I love Google and I use it constantly. But I can see its limitations, too. Google is not necessarily the last word in subjects which are enriched by discussion, especially discussion among a group of people familiar to the information seeker, a kind of peer group. Some questions really are answered better by human beings reading them, not by pages which happen to show up at the top of a Google search.