Users who have participated in a lot of Drops campaigns over the years have accumulated hundreds upon hundreds (if not thousands) of Drops, and these all have to load when you navigate to your Drops inventory at https://www.twitch.tv/drops/inventory
This can make the page load slowly and perform worse than expected. Adding pagination would limit the amount of claimed drops a user would be presented with at a time, thus cutting down on loading time and improving page performance.