It helps. Let's take the example of numbers. You begin learning as a child with 1, 2, 3... Everything is an integer and begins with one. Rapidly, you learn the notion of 0. And then at school, at some point, come the negative numbers. You have to "throw the ladder" that numbers are integer and begin with 1. You still know how to count, indeed in a more complex way.

Let's say you begin with markup, and just put the style as a tag to begin with. At some point, you know what a style does, but you have to throw the ladder that it has to be inside the markup, and externalize it to .css file.

Learning is a progressive experience.

I think it might be interpreted as "throwing away" the ladder-based technique, not forgetting about it.

So, for example, I might learn to build a Rails app using the scaffolding system, but once I know Rails well, I wouldn't.

No, you're still on top of the mountain, you just no longer need the rungs.

Maybe not, but I can still appreciate them and remember what they offered.