Earlier quoted context omitted.
But I guess that's exactly the point, isn't it? The fact that Flask/Express are so bare bones, you end up learning a lot, so for learning purposes makes a lot of sense.
You have a point, in a more relax comment, how much learning is enough? As personal opinion just reading the documentation of your tool of choice can lead to vast amount of knowledge, default params, recommended practices, all of that is included in a well documented project, but how much should I dig into the rabbit's hole when using node?.
In my case, I want to have a good base knowledge before leaning on any kind of "magic". I got into Python with the MIT course on EDX and got bit by the programming bug. I decided to try and get into the web dev stack, so I started to dive into JS too. Now I want to start to build stuff, and the reason why I asked the question in my first post is because it may be easier to just go deep into one language (can't do web dev without JS), since I am so inexperienced.