It's not really new, except perhaps it being more indie now. In most (but not all) niches over the years, the paid, formal published for-profit books have provided the best documentation, right back to the 70s, through O'Reilly's catalogue (he got rich for a reason), through MSDN, and right up to now. Indeed, it's possibly better now because a single author can do it all on their own.

Just FYI: du jour. De jure means something else.