There's a small feature that I think plays a disproportionately large role in why so many people seem to be addicted to social media: Infinite Scrolling
When you see numbered pages, or even something like a Next / Previous links, there's an internal boundary marker that gets registered that notifies you that a segment or a content block has ended
This hint is entirely missing in infinite scrolling and it's quite easy to keep going until the battery dies or real life demands immediate attention