You are right. The exercises are heavy in one area. Still, for starting in a new language can be helpful: you have to do in/out with files. Data structures, and you will be using all flow control. So you will not be an ace, but can help to get started.

I know people who make some arbitrary extra restriction, like “no library at all” which can help to learn the basics of a language.

The downside I see is that suddenly you are solving algorithmic problems, which some times are bot trivial, and at the same time struggling with a new language.