I agree with much of what is said in this piece, but this bit of misinformation jumped out at me:
DuckDuckGo is not a search engine. It’s more aptly described as a search engine frontend. They do handle features like bangs and instant answers internally, but their actual search results come from third-parties like Bing. They don’t operate a crawler for their search results, and are not independent.
I’ve seen this mentioned elsewhere as well, but it’s not entirely true. DuckDuckGo does operate a web crawler for their search results. They have partnered with third-parties like Bing, but my understanding is that this is to supplement the results they provide in searches.