For those who want a better explanation of Sky's capabilities, I recommend Federico Viticci's article (linked from the Tao of Mac article but the links are not distinctive): https://www.macstories.net/stories/sky-for-mac-preview
He goes fairly deep based on two weeks of usage.
People complained about the links being too visible, so they are only visible once per article now, and I make sure to highlight them on hover over a paragraph. I guess I will never please everyone :)