When you see comments on a post, most people click the post title, which takes you to the top of the thread.
But the last commenter's profile circle (I call them bubbles) is actually a hyperlink that jumps you straight to that person's comment, (at least most of the time) whether it's at the end of the thread or somewhere in the middle, wherever they happened to post.
For long threads, or if you're on Skoolers a lot, this shortcut can save you real time.