You can. In fact, Chrome automatically creates search engines for any site you search on. I can search Amazon by typing "Am<tab><query><enter>" in the address bar for example, and Chrome learned how to do that automatically despite not having any knowledge of how Amazon's search system works when I first installed it.
I guess the only difference is that with this change, DDG is available as a search engine by default with a blank install, even before you've actually used it.
I guess the only difference is that with this change, DDG is available as a search engine by default with a blank install, even before you've actually used it.