Endless scrolling strains browser resources, and when the browser finally crashes and releases its memory, it has no record of the position you were in. Pagination doesn't cost much on the server side (unless you try to keep an accurate count at all times, but that's rarely important). Pushing the work to the client may be seductive because it's the newer technique, but it doesn't even provide increased responsiveness because web developers tend to completely disregard the costs of client-side inefficiency (particularly for memory, which sees a sort of tragedy of the commons).