If one more voice helps, let me wholeheartedly add mine to the call for date filtering. If a bang search to Google or other search engine is comparable to going there directly (which the post by Zacbranni copied below says it is) as far as privacy/tracking is concerned, what's the point? And the post he mentions refers to adding the date sort but not a date filter.

The post I refer to:

!bangs act as redirects so, after you land on that page, you're subject to that site's privacy policy. Showing Google's results on our page would be a violation of their terms of service but we hope to fill that gap by providing a lot more date functionality. On dates, check out: 
posted by [Old Forum guest] • 5 years and 26 days ago Link

We're working on integrating more date options but, because of the multiple sources we use, it's difficult to do. It's definitely on our list, though! 


DuckDuckGo Community Manager
posted by zac Staff5 years and 26 days ago Link