I want things in chronological order so I can tell if I have missed any post. But that doesn't mean I need to read every post. I do want to be able to decide for myself from the list what I view as a "top story". So I have them sort by date. and when I've scrolled back to something I know I've seen then I don't need to keep scrolling back. When things are random, I get stuff I've already seen mixed in with new stuff. That is not a very good user experience IMO.