There is a fundamental difference between reference material, where only the final version is relevant, and tutorial material, where the evolution is also important. You keep making similar comments in this discussion where you compare this tutorial/exposition format to typical reference documentation, but they're solving different problems and reasonable assumptions in one case don't necessarily hold in the other.

In particular, presenting this sort of tutorial/exposition material as you suggest could make the document much longer, but worse, the reader would have to keep looking at almost the same code snippet and figuring out what changed at each step instead of having it demonstrated by the animation effect. That is a significant mental overhead, and it's a recurring pain point when teaching programming subjects that can be remedied by using something that actively shows the progression. I've used similar techniques where some example code evolves with simple animations in both presentations and private documentation, and it generally seems to be effective at communicating the intended ideas and well received by the target audience.