It allows you to search a collection of sources for information. Maybe you want to search a group of 20 tech blogs that you trust, just as one example.
Before Google, this was a common technique used by search engines to direct users to trusted content sources.
I use duck as my first choice, but unless I'm just looking up one word, it doesn't find much useful. If I look for a specific question, duck doesn't work at all and I have to go back to google. google is way worse than it used to be, but it's still better than any other I have found yet.
I guess the times duckduckgo works better for me is when I'm looking for answers Google is able to identify, but chooses to filter out, like in psychedelic trip reports
Look up something like schnitzel and you'll have 7 paragraphs of AI slop, telling you about the author, the history of the dish, the weather, a new cookbook for sale, before you get to the actual recipe