The text in their help is confusing, but it kind of implies that their crawler is for answers only, and that web results come from Bing and yahoo (which is powered by Bing).
I don't know why they would, though.
They get paid and it doesn't steal traffic from them.
Unless Bing releases its own anonymous mode and DDG becomes a competitor.
Then they could charge more or force DDG to display "powered by Bing" in the logo. That would be the end of DDG.
This. I'll never understand the hype about bangs when you can do the same by typing a letter and tab your browser.
en. <tab> to search on English Wikipedia, etc.
Having to do ! seems awkward, plus you have to remember the letters.