Actually, I think news articles don't have clear-cut layers, but actually gradually dive deeper.

The original motivation were layout considerations for printed newspapers with limited space. With all articles pre-written like that, an editor could arrange them on the final layout and cut off at the end at discretion while keeping the most relevant information given the remaining space.

That being said, I don't think this is too relevant for your idea, just an interesting anecdote.

Have you seen axios.com? They used to start off with short paragraph bites of news articles, that had a one-click go deeper to an in-depth piece.

I didn't but I just checked it out now. Interesting I'd say. They have the short-version and the max-version. The tool I'd like to make would allow you to do all the in-between versions