Presumably, this is because their results are really just from someone else's index (e.g. Bing). If that's the case, then it's not really DDG doing the curating

Presumably, this is because their results are really just from someone else's index (e.g. Bing). If that's the case, then it's not really DDG doing the curating or filtering. The real test will come if they ever switch over to their own crawl and search.