I think this is a real issue, and I am glad that DDG is addressing it. This is a more-compelling take on the tracking issue IMO.

What I'd really like to see, is a search engine to allow me to do both. I'd like to have a profile (that didn't use my name), and when I wanted to, I could click a result as 'useful'. This would go into my personal algorithm. I could then toggle between filtered search, or unfiltered search, whenever I like.

It might even be useful to build search filter categories. But I'd keep that a bit buried for the power users.