I think the ideal solution will be some sort of middle ground, where much of the drilling down will be done by clicking on specific words or sentences, but a slider would allow you to generally expand more text in the article, for things that aren't exactly related to other sentences.

It does take a bit of doing, and drilling down to another layer should also be able to delete text, so the wording flows better.

If you want to talk about this more, feel free to send me an email, I find this problem very interesting.