It is cognitive dissonance, with DDG. A large proportion of their users are exactly the sort of people who will not thoughtlessly install unnecessary extensions

It is cognitive dissonance, with DDG. A large proportion of their users are exactly the sort of people who will not thoughtlessly install unnecessary extensions into their browsers. It is increasing attack surface, when minimizing should be a goal of privacy services. By the time you end up at DDG, you usually have been trained not to click on untrusted links and not to install dodgy browser extensions 'for your chance to win', and then confronted with a push to install what appears to all intents and purposes to be a dodgy browser extension.