Bing contract prohibits DuckDuckGo from completely blocking Microsoft tracking. Their response

Yegg: This title is very misleading (and really should be changed).
This is not about search. To be clear, when you load our search results, you are completely anonymous, including ads. For ads, we actually worked with Microsoft to make ad clicks privacy protected as well. From our public ads page, "Microsoft Advertising does not associate your ad-click behavior with a user profile." This page is linked to next to every Microsoft ad that is served on our search engine …

bing blocking contract duckduckgo microsoft privacy response tracking