The infinity scrolling appeals to our hunger for more and more stimuli, which in turn has us spend more time browsing the network. That longer exposure allows FB to monetise even further.
One thing that worries me – and it's not discussed in the article – is the loss of productivity, as well as cost of the opportunity for the individual.
In fact, individuals who become addicted to social networks may carry a psychological cost as well, which in turn reflects on the productivity of the individual inside the global economy system.
You could argue that time spent on Facebook would've been spent on other leisure activities anyway. But is it true? Much of this time is now spent due to compulsive behaviour, every 5 minutes, 10 minutes, as soon as you wake up, before going to bed, etc.