If your content stream includes every post your friends make, every comment they add, every post they like, every event they're interested in or join in on and

If your content stream includes every post your friends make, every comment they add, every post they like, every event they're interested in or join in on and it was sorted chronologically then you would never be able to scroll past the immediate present. It would just constantly generate new content as quickly as you can scroll. I'm glad they sort by relevance and time is just one small factor in relevance.