> He also advocate not using underline to denote links.
    >In his practical typography book he practically hides all hyperlinks.

I think that's a fine, defensible stylistic choice. When reading a paragraph of prose, I find it INTERRUPTS MY FLOW if there is a jarring style change in the middle of a sentence, as in this one.

The visual style of a hyperlink is only relevant to the point that you know the hyperlink is there and can find it when you want to click on it. Most of the time, that's not a goal, so you want it to fade into the background unless the user has indicated that is their goal.

So my preferred style for hyperlinks in prose is a color that's right at the just-noticeable difference [1] relative the normal text. When you mouse over the paragraph, which indicates you are intending to click, the contrast increases.

[1]: https://en.wikipedia.org/wiki/Just-noticeable_difference