[dirkt]

What is nearly always missing is some sort of overview that explains you which parts are there, what are they good for, and how they work together.

Either these are very rare, or there are hard to google because they are drowned out by the many tutorials.

When you follow a tutorial, you are shown a very specific way of doing things (which often isn't up to date, with no indication that in the meantime this way has been replaced by another way).

And while that's very helpful for a beginner, it isn't as helpful for an experienced programmer, especially if he or she is having a problem that needs a slightly different way of doing things, and the missing information is just "instead of X, you can also do Y here".

And references don't answer these questions, unless you work through them from top to bottom (which usually takes more time than you have).