We recently covered a story about LinuxMint using DuckDuckGo as the default search engine. The LinuxMint project will generate revenue through DDG. We do support LinuxMint and have nothing against them using DDG as the default search engine.
However, the primary goal of a search engine is to show relevant results. We are aware that Microsoft's Bing doesn't show quite a lot of open source projects on the first page. LibreOffice, the default office suite of all major GNU/Linux based operating systems is missing from Bing's first page.
Some readers were pointing at LibreOffice being the second result on DDG, which is not correct. DDG is not at all showing any results from LibreOffice.org, similar to Bing. So, DuckDuckGo and Bing users will never land on Mozilla.org or LibreOffice pages.
Here is a quick video.