If I want Google results, it's a heck of a lot faster, easier, and natural to just Google it instead of adding some kind of search operator BS to my query. I used DDG for a while (a long time ago, admittedly) and basically had to !g every query I ran in order to get acceptable results. In the end, I gave up because it was just adding typing and thinking time to search.
I suppose one could argue that the interface lacks some of the annoyances of Google, but I feel like quality and speed are the most desirable traits of a search engine (in that order). If we're just using somebody else's results anyway then why should we accept a slowdown?
Also I frequently find nowadays that Goog and DDG provide very very very similar results for most queries for which I dissatisfied enough with DDG to try Goog.
I don't mind since it saves me from having to go into "privacy defensive" mode to interact with the big G.