Why does Qutebrowser use DuckDuckGo ?
Qutebrowser: qutebrowser is a web browser for Linux, Windows, and macOS operating systems with vim-style key bindings and a minimal GUI. Qutebrowser:  It uses DuckDuckGo as the default search engine. DuckDuckGo:  DuckDuckGo emphasizes returning the best results, rather than the most results, and generates those results from over 400 individual sources, including key crowdsourced sites such as Wikipedia, and other search engines like Bing, Yahoo!, Yandex, and Yummly.
emphasizes returning the best results