You don't use DDG because it's better than Google. You use it because it's not Google. So of course they remind people of that constantly. And... Google can take it.
I do think it's fair to complain that duck.com redirects to google.com if you're DDG. It's also fair for Google to do it anyway! Both sides are playing their part and that's okay. (Google did sell it to DDG, though, so good on them.)
I used to work at Mozilla, and it's crazy how easily a large company can crush you by... just existing. Google can funnel people to Google Search from Android, Chrome, Gmail, etc. Google is the defacto default, and DDG has to fight desperately for anyone to care.