Traditional distros have decades of guides, forum posts, and StackExchange answers. Atomic systems? Not nearly as much. When something breaks at 2am, knowing there's a million Google results for your error message is comforting.
This is my reason. I've been using Arch exclusively for a few years, but have used it on and off since 2008. I still don't consider myself an expert by any means, and I frequently pull the docs and old forum threads to solve issues I run into.
Documentation is the most important deciding factor for me. I didn't use more fully featured distributions, even if they were "easier" becuase if I can't look up the answer, and I have to live with something because I don't know what button to press... I mean you may as well just give me a windows box again.