writing programing language tutorial isn't easy, and is extremely time consuming. Suppose you are reading a book or a doc. In few minutes, or even after a hour with coding, you understood it, and can employ it right away in your project or job. But, if you want to write a tutorial of what you just learned, it'll take 10 folds more time. Because, first of all you have to give context of why, and this aspect often takes some research by itself. Then, you have to have a good understanding of the whole instead of just the parts you just understood, because otherwise its like the blind men feeling the elephant and you can't say to readers that a elephant is pillar-like and period (this happens to haskell monad blogs). Then, you need to give good examples. Proper ones, and ones that are idiomatic, industrial accepted. So, it's like you have to have a survey of sorts, either from experience or have read tons about it. And, if you are like me, have idiosyncratic bent on things, you need to put things into style yet respect all the above mentioned issues. That doubles or triples the time and effort.
note that, this is not to imply that coding a project is easier. They are quite different endeavors. For example, if you are coding a project, once you read something, you can put to use right away, but, then you have 100 other details and complexities you need to solve, that you otherwise don't have to deal with if you are writing a tutorial. Tutorials typically deal only with clean, crystallized, account.