I get it. It's just that I'm not a beginning programmer. I mean, unless the site is only for novices with zero programming skill, you're requiring all intermediate programmers to relearn stuff they've already mastered.
Also, I wanted to browse around the lessons in order to evaluate the quality of the site so that I could decide whether to recommend the site to non-programmer friends.
That should have been the first thing you said. :)
But such tutorials are obviously for rank beginners, experienced programmers don't use these kinds of sites. Unless it's a dramatic jump, like from COBOL to Haskell, to learn a new language they go straight to the language's documentation:
There's a good reason for this, which I will explain with an analogy:
Lesson 1: Write the Great American Novel.
Lesson 2: Learn how to write engaging, readable short stories.
Lesson 3: Learn how to write internally consistent essays.
Lesson 4: Learn how to write coherent paragraphs.
Lesson 5: Learn how to structure grammatically correct sentences.
Lesson 6 Learn how to use and spell common English words.
Lesson 7: Learn how to enter text on a keyboard.
Get it? Lessons have a natural order, and each lesson requires what was learned beforehand.