[pahbloo]

This "depth slider" is called the Inverted Pyramid [0]. The first paragraph has the main information (aka tl;dr). The next the secondary points. And as a reader, you just have to keep reading as you want more details. You know the next few paragraphs don't have more important information than what you've already read.

That's how the print media wrote their articles. They've already sold the paper/magazine to you, so now the goal was to make you feel like you have as much information as you would like with as little effort as possible, so you're willing to buy the next issue.

Nowadays, with the attention economy, the writing style has changed. The main objective is to keep the user reading for as long as possible.

[0]https://en.wikipedia.org/wiki/Inverted_pyramid_(journalism)