It's not just speed reading that gets this wrong, it's also book summaries, and listening to podcasts on 1.5x.
The point of a lot of writing is to transform you either directly or by allowing you time to think and make connections between the book and what's in your own head already.
Articles like this reframe the goal to be about quality. What bigger goal is reading supposed to do for you? A lot of times slowing down and applying reading skills (even note taking) is actually a better way to achieve your bigger goal for why you want to read something.
And if it's not worth slowing down, then is it worth reading at all?