Good documentation is great to have. Here's the thing though. If you need documentation to use an OS... That just proves that it really is harder for people to use.
Mint and Windows both share the ability to pick it up and use it for the majority of what most people do. Arch is like the textbook example of having to learn a bunch in order to use Linux.
Both OS are hard if you don't know how to use them.
Both OS are easy if you know how to use them.
Linux's problem is fragmentation. There's not a single OS that many people are familiar with like Windows. Instead there's hundreds of different distros that all function in a variety of different ways. Even if a person learns to do something on Mint or Ubuntu, they will be completely lost trying to do the same thing on Fedora or Arch.