That is an interesting website, but they do something different than what I was looking for. They have a staff writing educational content. I was looking more for a platform where content written by anyone from anywhere would be linked, so I could find best materials for learning something without being limited to one source.

In fact, I think the site you linked illustrates the problem. There are many such sites scattered all over the web. I surely won't find courses for any given topic on one site. And I might find better courses somewhere else. But Google will hardly help me with that, because they cannot know which courses are good, only students could possibly know. That's why I suggested there be a website that gathers links to courses (and other formats) which are rated by people who studied them.