If the user submits a GET request to DDG from the commandline with Javascript disabled, then all results links are prefixed with the address of a DDG server, e.g., https://example.com becomes https://duckduckgo.com/l/uddg=https%3A%2F%2Fexample.com Whatever the reasons may be for this decision, it allows DDG to track all links that the user follows from the results page. That is no better than Google. It is not a priv…
It's meant so that the sites you click on can't see your search queries via the Referer HTTP header.
You can turn that off in DDG's settings[1] under the privacy tab. It's the "Redirect" switch. They explain more about it[2]. Basically, it's a privacy choice they give you between preventing sites you visit from seeing your search queries or preventing DDG from seeing what you clicked on.
If you want, you can prevent both by enabling their settings option to use POST instead of GET in their search. Then you can disable the redirect and the sites won't be able to see your search query from Referer, because it would have been passed through the request body instead of URL parameters. However, that's going to prevent you from being able to have your searches in your browser history.
EDIT: I now note why you mentioned javascript and why the Referer option talks about being needed on old browsers. It seems that when javascript is enabled, they do something else to ensure that Referer doesn't leak search queries without passing info on what you clicked on to DDG. That means that, by default on a typical browser, both leaks are prevented. That's pretty neat.