vgo is actually much, much simpler than dep. The sheer number of words in Russ Cox's series of blog posts belies its simplicity. vgo doesn't need a SAT solver. If you look at many of the issues dep is struggling with, they're related to solving N libraries with transitive dependencies up the wazoo.
Cox's long treatise reflects the complexity of the problem space. Developers tend to brush off package management as being simple. But once you include range-based version constraints and transitive dependencies, it gets a bit messier. Look at NPM and Yarn; they're still struggling to get all the details right. On the other hand, there's Ruby's Bundler. It came out in 2009, RubyGems in 2004, and I've never had a single issue with the toolchain (other than messing up my own constraints). I don't know what kind of magic elixir they were drinking, but somehow those guys managed to nail it from day one.