That’s not quite accurate. If you’re in a topic with 5,000 posts and click the end date on the timeline (or any other method of jumping to the end other than scrolling) you don’t actually load every post in-between. “Pages” of replies are loaded in/out behind the scenes, so if you skip to the end only the most recent batch of posts load.
If you start reading and come back later, your position is saved too… so you shouldn’t need to “binge” an entire topic any differently than with paginated forums.