When DDG doesn't yield the results I'm looking for, I will frequently try Google, but more and more I find that if DuckDuckGo can't find the results that I want, then neither can Google. What Google can do however, is annoy me with results that it knows to be wrong, because it is excluded the most specific part of my query. Google will remove the bit that absolutely had to be in the query, to get more hits on the majority of the remaining words.
In the end, I think most people could use either Google, Bing or DuckDuckGo and be happy with the results. It's just that we're stuck on "Google is the best search engine", and while that may be true in some technical sense, many of the other search engines are just as good for most of us.