Why do people always focus on the code part? Even when the code is written in a language you don't understand, you can contribute by making the documentation, install process, or general community better.

In the article one of the questions asked is, "Is the documentation good?" If it's not, but you use and like the project, that is your opportunity. Perhaps you can see there are a lot of bugs filed, but nobody is triaging them. Even when you don't know the programming language the project uses, getting or making reproducible test cases for bugs is something you can do.

I completely agree with the "relatedness" aspect. If you're not using a project in your day-to-day work it's hard to stay involved with it. The best Open Source developers are those who understand the perspective of the users, because they are a user.