For better or worse, it also improves analytics for the publisher— they can measure what proportion of readers made it to page 2, and of those, how long they spent on page 1.
(Yes, some of that could be done with scroll tracking too, "clicked to view page 2" is still a very strong signal of engagement.)
(Yes, some of that could be done with scroll tracking too, "clicked to view page 2" is still a very strong signal of engagement.)