How?
Personally, I think it’s nice to have the content instantly available and not having to go to a website for it but I can see how for content producers this means wrapping their websites and making money out of their content.
Also, DDG's "Instant Answers are open source and are maintained on GitHub, where anyone can build or work on them". https://en.wikipedia.org/wiki/DuckDuckGo
It's not the same sort of massive web-scraping click-stealing operation as Google's OneBox.