I think tutorials should be vaguer because “A [vague tutorial] would get the reader playing instead of reading and help them practice composing code instead of copying it.”
In a typical tutorial, all of the code is inline with the text, which tries to explain it line-by-line. In a vague tutorial, you’d get just enough information to write the code yourself. Some code would be given as a scaffold with blanks you fill in.
This is very much like how coding interviews work, so doing a series of vague tutorials would be good training for them.
This means that the sites that are doing training for coding interview (e.g. TopCoder and HackerRank) are to some extent vague tutorial writers. It’s interesting that they also gamify their sites (mostly via ranking), which gets at the theme of many of my posts, although I think gamification is not as good as playability.
In my last job hunt, I knew my target employers gave very hard data-structure/algorithmic style coding interviews, so I spent weeks on TopCoder (most failing) before I applied. The main things I got out of it was deciphering specifications under time pressure and iterative development. Both of these skills are invaluable when doing a coding interview, because unfortunately, tech job interviews are mostly auditions.