That's basically false. There is a learning curve that people seem to ignore when using search engines. It's not obvious, but Google vs Bing work a bit different and the type of queries each one likes are different. I use a Bing based engine as my daily driver and when I'm working, 9/10 searches are successful in the first couple results. When I'm out and about searching for something casual on my phone, that's usually 10/10.
I don't think it's false. It highly depends on what you're searching for. There are cases where DDG isn't good enough and I don't think the user is responsible for it in any way. Two examples off the top of my head:
* If you're searching something not in english. I'm french and DDG is my default search engine, but I have to switch to other search engines a lot when searching in french.
* When searching very technical things, like a very specific and rare error message. Good luck finding anything relevant with DDG.
As much as I'd like to use DDG for 100% of my research, I just can't.